(CNN) Isaiah Thomas' shoulders heaved. He sat on the Boston Celtics sideline at TD Garden, sobbing.
It was Easter Sunday, and the Celtics, led by the 28-year-old Thomas, were set to start their NBA playoff run at TD Garden in Boston. His team had earned the No. 1 seed in the Eastern Conference and was preparing to face the eighth-seeded Chicago Bulls in the first round.
But the game all but paled into insignificance. Just one day earlier, Thomas' younger sister, Chyna Thomas, was killed in a single-car crash in Washington state. She was 22 years old. According to police, just after 5 a.m. local time April 15, her vehicle drifted onto the left shoulder of Interstate 5 and slammed into a pole. She was pronounced dead at the scene.
Before Game 1 on April 16, Thomas observed a moment of silence dedicated to his sister.
Tipoff for Game 1 wasn't far way, but the Celtics' point guard continued to cry. Teammates came by to put an arm around him or give him a hug.
It was a heartbreaking sight. Would their point guard play? Could he play?
"I never could have imagined a day where my little sister, Chyna, wouldn't be here," Thomas later said in a statement. "She and my family are everything to me, so the pain I am feeling right now is impossible to put into words. This has been without question the hardest week of my life."
'RIP Lil Sis'
Even though he's one of the shortest players in the NBA -- he's listed at 5 feet, 9 inches -- Thomas regularly comes up big. It started almost immediately with his namesake.
Thomas was named after NBA legend Isiah Thomas when his father, James, lost a friendly wager on a Lakers vs. Pistons playoff game in 1989. He had the famous name, but because of his height, Thomas had to prove to the league that he belonged. He played three years for the University of Washington and was selected by the Sacramento Kings as the 60th and final pick in the 2011 NBA Draft.
The Kings traded Thomas to the Phoenix Suns in 2014, and then he was sent to Boston as part of a trade in 2015. He has thrived with the Celtics, leading the team in scoring, and is a two-time NBA All-Star.
It was a long road to success. But Thomas had never experienced adversity like this.
In Game 1, Thomas paid tribute to his late sister with messages on his shoes.
A day after the tragedy, the TD Garden lights went dark for player introductions ahead of Game 1. A moment of silence was held for Chyna Thomas as her brother continued to wipe tears from his face.
And then, with the words "Chyna," "I love you," "4-15-17" and "RIP Lil Sis" visible on his shoes, Thomas took the court. And he didn't just play. He couldn't be stopped.
Thomas led Boston with 33 points and the crowd roared every time he scored.
Low draft picks who became NBA superstars
Isaiah Thomas has been the driving force for the Boston Celtics, the Eastern Conference's No. 1 seed going into the NBA playoffs. The point guard might only be 5-foot-9, but he finished the regular season as the league's third-leading scorer (28.9 points a game). What might be even more amazing was that Thomas was picked dead last -- 60th overall -- in the 2011 NBA Draft. Here are some more
NBA superstars who weren't high draft picks.
Tony Parker, left, and Manu Ginobili celebrate after the San Antonio Spurs won the 2003 NBA Finals. Both Parker and Ginobili were draft steals who came from outside of the United States. Ginobili, an Argentine, was taken 57th overall in 1999. Parker, a Frenchman, went 28th overall in 2001. The two have won four championships with San Antonio and are likely Hall of Famers.
Golden State's Draymond Green was taken in the second round, 35th overall, in 2012. Many viewed him as undersized for the power forward position. But he's already become one of the league's best defensive players, making two All-Star teams and leading the league in steals this season. He was a major contributor to the Warriors' title in 2015.
Speaking of defense, there aren't many better at it than the Clippers' DeAndre Jordan. Jordan, like Green, was chosen No. 35 in the draft. And like Green, he made the league's All-Defensive Team in 2015 and 2016. Jordan also led the league in rebounding in 2014 and 2015.
Dennis Rodman, perhaps the greatest rebounder in NBA history, went 27th overall in the 1986 NBA Draft. He played college at Southeastern Oklahoma State, a small NAIA school.
Joe Dumars played with Rodman on the Detroit Pistons team that won back-to-back titles in 1989 and 1990. Dumars made six All-Star teams during his Hall of Fame career. Not bad for a guy taken 18th overall out of McNeese State.
OK, the 13th overall pick isn't exactly a low draft pick. But considering it was Kobe Bryant -- one of the league's greatest players of all time -- you have to consider it one of the biggest draft steals in league history. Bryant was taken by the Charlotte Hornets and traded to the Los Angeles Lakers on draft night in 1996. He spent 20 seasons with the Lakers, winning five NBA titles and making 18 All-Star teams.
Steve Nash was drafted just two picks after Bryant in 1996. He became one of the league's best-ever point guards. Nash made eight All-Star teams in his career, and he was also the league MVP in 2005 and 2006.
The Utah Jazz got two Hall of Famers in back-to-back drafts. Karl Malone, left, was the 13th overall draft pick in 1985. John Stockton, right, was the 16th overall pick a year earlier. The two were perennial All-Stars who played together for nearly their entire careers. They also starred on the iconic "Dream Team" -- the U.S. Olympic team that won gold in 1992.
Clyde "The Glide" Drexler, another member of the 1992 "Dream Team," was the 14th overall pick in 1983. He made 10 All-Star teams and won a title with Houston in 1995. He was inducted into the Hall of Fame in 2004.
Alex English, right, was a prolific scorer who made eight All-Star teams in his Hall of Fame career. He was drafted 23rd overall in 1976.
Dennis Johnson won three NBA titles in his Hall of Fame career: one with Seattle and two with Boston. The point guard, one of the best defensive players of his era, was drafted 29th overall in 1976.
Nate "Tiny" Archibald was taken 19th overall in 1970. Three seasons later, he led the league in points and assists. Archibald made six All-Star teams and won a title with Boston in 1981. He made the Hall of Fame in 1991.
Jimmy Butler has blossomed into one of the league's best players since Chicago took him 30th overall in 2011. He's made the All-Star team the last three seasons and become one of the league's best defensive players.
Philadelphia took Maurice Cheeks with the 36th pick in 1978. The point guard won a title with the Sixers in 1983 and finished his career as the league's all-time leader in steals. He also averaged nearly seven assists a game, and Philadelphia retired his number.
Kawhi Leonard was taken 15th overall in 2011. Indiana traded him to San Antonio on draft night, and he's become yet another steal for the Spurs. He was MVP of the NBA Finals in 2014, and he's made the last two All-Star teams.
The Celtics didn't win Game 1 that night, losing to the Bulls 106-102. They also lost Game 2, 111-97, as Thomas had a team-high 20 points.
But despite the devastating loss of his sister, Thomas hasn't missed any games -- he flew out to Tacoma, Washington, to be with his family between Games 2 and 3 -- while giving his all for the Celtics each night.
Boston clawed back into the series, winning Game 3, 104-87, thanks in part to his 16 points and nine assists.
And on Sunday in Chicago, the Celtics, led by Thomas' 33 points and seven assists, defeated the Bulls 104-95 to even the best-of-seven series at 2-2.
"Mentally and emotionally I'm not here," Thomas said following Sunday's win. "I just feed off what the guys give me. They give me a lot of confidence, so I can't do without those guys. They believe in me, and being here is what makes me, I guess, sane and makes me feel somewhat normal through this tough time."
'What he's done has been remarkable'
After Game 4, Celtics head coach Brad Stevens shook his head as he marveled on how Thomas has handled the last week.
"I can't believe it," Stevens said. "I tried to say that earlier this week, but what he's been through and the day to day is just, it's unfathomable the way that he's performed on the court. I mean, it's been really incredible. It didn't go our way in Boston, but the guys were resilient enough to come back and tie this up. But we've got a long way to go. What he's done has been remarkable."
NBA Finals: The greatest records
The Boston Celtics celebrate after winning the NBA championship in June 2008. It was the 17th title for the Celtics -- the most in league history. Take a look back at some of the greatest records set in the NBA Finals.
Most NBA titles (player): Bill Russell, seen here with legendary coach Red Auerbach, won 11 titles in his 13 NBA seasons. The big man won all of them with Boston, starting in 1957 and ending in 1969.
Most career points in the NBA Finals: Nobody's scored more than Los Angeles Lakers guard Jerry West, who put up 1,679 points over nine NBA Finals. West and the Lakers usually ran into the buzz saw that was Boston in the 1960s, but they did win a title in 1972. Fun fact: The NBA logo is a silhouette of West.
Most points per game in an NBA Finals series: Michael Jordan and the Chicago Bulls won six NBA titles during his career. But "His Airness" might have been at his peak in 1993, when he averaged 41 points in a six-game victory over Dan Majerle and the Phoenix Suns.
Most points in an NBA Finals game: The Lakers' Elgin Baylor scored 61 points during a Finals game against Boston on April 14, 1962. The Lakers won that game but went on to lose the series in Game 7, pictured here.
Most common matchup in the NBA Finals: The Boston Celtics and the Los Angeles Lakers have played each other 12 times in the Finals. The Celtics won the first eight meetings, but the Lakers broke the streak in 1985 and 1987, pictured here. The teams also split a pair of Finals in the 21st century. While the Celtics have a league-best 17 titles, the Lakers are right behind them with 16. The Chicago Bulls are the next closest at six.
Most Finals MVP awards: Michael Jordan was named the Most Valuable Player for all six Finals he played in. The Bulls guard holds his 1998 award here next to head coach Phil Jackson.
Most 3-pointers made in an NBA Finals game: Golden State's Stephen Curry hit nine 3-pointers in Game 2 of the 2018 NBA Finals. He had 33 points as the Warriors took a 2-0 series lead over Cleveland.
Most assists in an NBA Finals game: The Lakers' Magic Johnson had 21 assists in Game 3 of the 1984 NBA Finals. Boston won the Finals that year, but Johnson and the Lakers got their revenge one year later.
Lowest-seeded team to win it all: The 1995 Houston Rockets -- led by future Hall of Famers Clyde Drexler and Hakeem Olajuwon -- were the Western Conference's sixth seed when they went on to win the title. The Rockets also won the championship in 1994.
Most blocks in an NBA Finals game: Dwight Howard blocks a shot by the Lakers' Pau Gasol during the 2009 NBA Finals. It was one of nine blocks the Orlando center had in Game 4.
Most steals in an NBA Finals game: They called him "Big Shot Bob" for his clutch shooting, but Robert Horry was a fierce defender as well. Horry had a record seven steals in Game 2 of the 1995 NBA Finals. Horry won seven titles during his career: two with the Houston Rockets, three with the Los Angeles Lakers and two with the San Antonio Spurs. Only one other player -- John Salley -- has won NBA titles with three different teams.
Stevens said his players had Monday off to get ready for Game 5, which is Wednesday in Boston. The Celtics need two more wins to advance. But they have one of the best players in the NBA in Thomas, and he has the support from his teammates as he grieves.
"They've been really important," Thomas said. "I mean, they've been everything. This organization is the best organization there is, from the people who work in the Garden to the players, the coaches, everybody who is a part of the Celtics. They've been supportive. The whole world has, really. I can't say enough about that."