10 times the normally mild-mannered Roger Federer went wild in the middle of a tennis match

1995: Roger Federer was always a "brat" when he was a young teenager, according to the former Nike director of tennis, Mike Nakajima, who met him around this time. Federer would apparently "smash rackets in a heartbeat."

Before Federer signed a sponsorship agreement with Uniqlo, he had a relationship with Nike that spanned across two decades. Nakajima, the clothing giant's former director, first met Federer in the mid-90s and though he said he was" really, really talented," he was "a bit of a brat on tour."

Federer changed when he watched highlights of a junior match involving him and the eventual world number one male player Marat Safin, but the only thing television showed were the lowlights — "yelling, screaming, smashing, throwing things." As Nakajima explains, they were both "bad boys on the court."

The scenes embarrassed Federerer and, according to Nakajima, he "vowed never to do that again."

Though he has tempered that behavior, he has not eradicated it completely. He still yells, screams, and smashes rackets.

Source: Sports Business podcast.

2005: In April, Federer threw his racket on the floor in a fit of frustration during the NASDAQ-100 Open final against emerging rival Rafa Nadal.

Federer and Nadal met in an epic encounter in Miami in 2005. Nadal, 18 at the time, stormed to a two-set lead, only to throw it away and lose 3-2, surrendering the title to the Swiss.

But the final is as notable for Federer's anger as much as it is for the quality of tennis as Federer threw his racket on the floor in a huff, something he argued post-match may have helped.

"I was missing one opportunity after another," he said, according to the BBC. "I just had enough. I threw it hard. Maybe it did me good, who knows?"

Source: BBC Sport.

2006: Nadal and Federer met once again at the Italian Open final in Rome, a match the ATP claimed "cemented their rivalry." It was also a match where Federer lost his focus, and shouted at Nadal's uncle Toni.

The Italian Open final in May 2006 emphasized Nadal and Federer's status as the sport's greatest stars, according to the ATP. It was won by Nadal, who extended his head-to-head record to four wins and one loss against Federer, after another ill-tempered showing from the Swiss.

Federer, with his seven Grand Slam titles to that point, was up against the upstart. One British coach called him "the toughest b------ the game had ever seen," according to The Guardian.

In Rome, Federer felt the full effect of losing out to his natural-born rival. Toward the end of the final, Federer lost his focus completely, turned to Nadal's uncle Toni and accused him of coaching illegally.

"He was coaching a little bit too much again today," Federer said after his loss. "Yeah, I caught him in the act."

Nadal, still a teenager at this time, offered the older Federer some sage advice. "He has to learn to be a gentleman even when he loses."

Source: ATP, The Guardian, and Tennis.com.

2009: In a semi-final loss to 20-year-old Novak Djokovic at the Miami Masters in April, Federer channeled his younger years as a tennis "brat" and smashed his racket.

Federer, one of today's most cheered-for athletes, was roundly booed in Florida's Tennis Center at Crandon Park.

He took an early lead in his semi-final against Djokovic, winning the first set 6-3, but then lost the next two sets.

He smashed a racket for the first time in almost eight years, threw the mangled remains at his stool, and was slapped with a code violation. He was booed by the crowd, and refused to shake hands with the chair umpire at the end of the match.

Needless to say, it was a performance to forget from Federer.

Source: The Guardian and The Telegraph.

2009: Roger Federer was hit with a $1,500 fine for swearing at the umpire during his US Open final loss to Juan Martin Del Potro.

At the end of the second set, Federer dropped an s-bomb at the chair umpire Jack Garner as he felt aggrieved that Del Potro was taking too long to make a challenge.

The reason for Federer's fury was because Del Potro's challenge overturned an "out" decision, which meant he was able to break Federer's serve and eventually take the second set.

Del Potro went on to win the title, much to Federer's chagrin when he was slapped with a $1,500 fine for his sweary outburst.

Source: The Telegraph and CNN.

2012: Three years later, Juan Martin Del Potro again brought the worst out of Federer when he turned on the French Open crowd and yelled at them to just "shut up."

The incident occured during the second set when Federer pumped a ball into the net, bringing an abrupt halt to an otherwise excellent rally.

Federer had already lost the first set, and went on to lose the second. However, he then won three in a row to book himself a semi-final place against Novak Djokovic.

John McEnroe, as famous for his anger as he is for his sporting ability, said at the time: "That's about as angry as you'll see Federer."

Obviously, McEnroe had not known about his racket-smashing past or, indeed, his racket-smashing future…

Source: Huffington Post.

2013: According to USA Today, Federer hurled an F-bomb at Andy Murray midway through their Australian Open semi-final.

Though it was left unsaid by the television commentators on the day, USA Today analyzed ESPN footage of the Australian Open semi-final match between Federer and Murray and discovered that during a "tense moment" Federer shouted "you f------ stopped" to Murray.

The cursing referred to a rally point won by Murray, after he hesitated on a shot as if "willing an out call from a linesman." USA Today reported that the pause "seemed to annoy Federer," who then swore at the Brit.

Though it was a talking point in the media, both players downplayed the significance of the event after the match — which Murray won. "Not relevant," Murray said at the time when asked about the f-bomb.

Source: USA Today.

2017: At the Swiss Indoors, Federer whacked his racket onto the net while he was losing to Juan Martin Del Potro, but rallied to get the win.

Federer went on to win the Swiss Indoors title, a tournament he has claimed a record nine times now, but he certainly did not have it all his own way in 2017 and vented his frustration in the middle of the tournament final.

The BBC called it a "rare show of emotion" from Federer, and it all began in the second set after he had already surrendered control in the first when he lost five points in a row in the tie-break.

This meant he had to battle back and win the next two sets to take the trophy, and he lost his cool in the second when he mishit a volley. Roger raged and whacked his racket into the net.

Regardless, he won the second set, the third, and the title.

Source: BBC.

2018: In the Australian Open semi-final against Hyeon Chung, Federer gave the chair umpire a tongue-lashing for his supposedly "bulls---" call.

Federer had already won the first set by a comfortable 6-1 score and was coasting to victory in the second, so he really had little right to be too upset at how the match was going.

But midway through the second, three break points to the good, Federer lost his cool when Chung's serve — initially ruled out — was overruled by another umpire, and awarded as in. Federer put the chair umpire on blast. "That's bulls---," he was heard saying.

Moments later, Chung retired because of "foot blisters," Sporting News reported. Federer won 6-1, 5-2, and proceeded into the final against Marin Cilic, which he won in five sets.

Source: Sporting News.

2018: During yet another match against Juan Martin Del Potro, Roger Federer was heard arguing with an umpire and seen smacking his racket on the ground before he crashed out of the Indian Wells final.

Roger Federer was incensed during his Indian Wells Masters final loss to Juan Martin Del Potro in March, last year.

Federer argued with the match umpire, smacked his racket on the ground, and lost his cool in the California heat.

The Swiss ace said at the time he was not sure how long it would take to get over the loss, but he bounced back well enough to win two ATP tournaments, claiming the Stuttgart Open trophy and the Swiss Indoors title, in addition to his previous wins at the Rotterdam Open and the Australian Open.

Source: Business Insider.