Denis Shapovalov's coach wasn't surprised that the teenager was able to keep his head while upsetting a tennis legend on centre court at the Rogers Cup.

Martin Laurendeau said Friday that he saw it a year ago when Shapovalov beat Australian star Nick Kyrgios in the Rogers Cup first round in Toronto and the 18-year-old's cool head was evident again this week with wins over 2009 U.S. Open champion Juan Martin Del Potro and former world No.1 Rafael Nadal.

"All the guys he's played up to, he takes it to them," said Laurendeau, who coaches Shapovalov and serves as Canada's Davis Cup captain. "He revels in that kind of atmosphere.

"He's like a fish in water when you put him on a big court against a big player. I don't know if you can teach that, but he has that and he's making the most of it."

Shapovalov, of Richmond Hill, Ont., posted one of the biggest wins in Canadian tennis history when he battled Nadal for two hours 45 minutes on Thursday night and pulled out the victory in a third-set tiebreaker. It was a back-and-forth match, with several break points saved on both sides. Shapovalov fell behind 3-0 in the tiebreaker, but a Nadal double fault and two aces gave the youngster the match.

Denis Shapovalov on Rogers Cup quarter-final: 'I'm very thankful that I'm in this position'0:33

At no time did the left-hander show any sign of cracking under the pressure. Instead, he fed off the deafening sound from the sellout crowd of 11,000 that cheered every point he won.

"It's a bit surreal to be able to, start to finish, last that long, produce quality tennis and go toe-to-toe with a legend like that," said Laurendeau. "It's just remarkable.

"I'm glad I was there to witness it. I'll remember it for a long time. It will certainly be a reference for him because he still has a lot of steps to go through. That's always going to be there for him, what he's able to do. Just continue to work towards his goal, which is being top 100, top 50, top 10 and, one day, contend for a Grand Slam."

Even 19-time grand slam winner Roger Federer of Switzerland was impressed watching Shapovalov on television at his hotel.

"I thought it was a fantastic match," said Federer. "It was exhilarating for the crowd, for the fans watching on TV, for Canadian tennis.

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Martin Laurendeau had a feeling star pupil Denis Shapovalov was going to do something special against Rafael Nadal. (Miguel Medina/AFP/Getty Images)

"I didn't expect it to be this way. I thought that Rafa was going to win in straights. Denis did a great job. I'm really happy for him. Rafa was all class. He was great. It was a good night for tennis in some ways."

It helped that Shapovalov had nothing to lose and could try risky shots, but so far, that seems to be part of the youngster's success. Federer first noticed it while watching the Canadian win the junior Wimbledon title in 2016.

"He was in all sorts of trouble," said Federer. "He kept going for the biggest shots: forehands, backhands and serves.

"I couldn't believe what he was doing. I guess for him it's somewhat normal to do that. Obviously it's risky and doesn't always play off. Doing that on Court 4 against a journeyman is a different story than doing it on center court, but not everybody can go up to that level. It seems that Denis has an extra gear.

"I think he's going to be a wonderful player."

Laurendeau said Shapovalov is still developing the physical and mental sides of the game. A major test came in February at a Davis Cup World Group series against Britain in Ottawa.

In a fit of anger, Shapovalov tried to smash a ball into the crowd, but instead struck chair umpire Arnaud Gabas in the face. Gabas needed surgery to repair a broken bone under his left eye. Shapovalov defaulted the match, which cost Canada the series, and was fined US$7,000 by the International Tennis Federation.

"How he's handled the February incident from the beginning was very impressive from anybody, even a veteran and a mature man, to face the consequences of what happened," said Laurendeau. "I think even more so for a teenager.

Match Wrap: Shapovalov upsets Nadal, advances to Rogers Cup quarter-finals2:04

"He's never shied away. The first thing on his mind was to apologize to everybody. He understood the consequences. He manned up. The biggest progress to me is that aspect — the mental, psychological aspect of his game. I mean, tactically, technically, physically he's improved. His biggest improvement to me has been how he's competing, how he's channelling and managing his emotions."

Only three weeks ago, Shapovalov was winning a Challenger event — one step below the ATP Tour — in Gatineau, Que.

He started the week ranked 143rd in the world, but the first three wins alone put him into the top 100.

But he will not be an ATP regular quite yet. He is not eligible to enter next week's event in Cincinnati and will instead play a Challenger tournament in Vancouver.

After that, he will try to qualify for the U.S. Open in New York.