(CNN) From John McEnroe's notorious outburst against a line judge at Wimbledon to Nick Kyrgios feebly tapping a serve over the net in anger -- it's not unusual to see tennis players lose their cool on the court.
But former world No. 1 Chris Evert -- who won 18 grand slam singles titles during the 1970s and '80s -- thinks tennis stars today are playing in a more pressurized environment.
"I think right now the game is bigger business," Evert told CNN's World Sport show."There's more money, there's more media, and there's social media which means you can't do anything in private anymore.
"Everybody knows everything about your life. I think that adds more pressure.
"The players travel with entourages of trainers and coaches and agents. We didn't have that in our day. There was less pressure for sure."
These days leading professional tennis players spend 11 months of the year traveling, fighting with jet lag and delays.
Swelling prize funds mean more is at stake financially, particularly during the grand slams.
At this year's Australian Open, which starts January 16, players will vie for a cut of the tournament-record $36 million purse on offer.
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So keeping calm under pressure can be key to success.
Stan Wawrinka, the reigning US Open champion, said mental toughness helped him win at Flushing Meadows last year.
Evert was also famed for keeping her cool on the court -- something she owed much of her success to. But comparing herself to rivals Steffi Graf and Martina Navratilova, Evert confesses that she "didn't have speed of movement that they had."
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"I didn't move as quickly as they did," the 62-year-old says. "Not to undermine my athletic ability, but I wasn't at their level, so I feel like I made up for it in the mental department.
"I stayed cool under pressure, I played every point like it was match point. It worked for me."