MIAMI (AFP, REUTERS) - Defending champion John Isner ended Canadian teen Felix Auger-Aliassime's dream run on Friday (March 29) and advanced to the ATP Miami Open final with a 7-6 (7-3), 7-6 (7-4) triumph.
Backed by his huge serve, the 33 year-old American fired his 21st ace to complete the victory after one hour and 53 minutes to book a spot in Sunday's final against Roger Federer.
The Swiss legend cruised into his fifth final here in Florida with an impressive 6-2, 6-4 victory against another Canadian teenager, Denis Shapovalov, in the later semi-final.
"It's amazing to be back in the final," said Isner, who hit 32 winners compared to 20 by Auger-Aliassime. "I am so happy to be one match away from defending the title."
The youngster from Montreal competed confidently in the biggest match of his career but will rue the chances that escaped him after being broken while serving for the first and second set.
"To break while Felix was serving for both sets was unusual but I have felt comfortable all tournament and feel I am playing well," Isner said.
There was a huge buzz surrounding the 18-year-old Canadian in the lead up to his first-ever ATP Masters semi-final, a spotlight brightening through his brilliant run from qualifying to the last four.
Against Shapovalov, 20-time Grand Slam champion Federer was dominant in service and broke the 19-year-old three times.
"I enjoyed it. I think I played very well. I had to," he told reporters.
"Because I think when you let Denis play, he's got some serious power, and he gets rhythm going. He can really put you in uncomfortable situations.
"So I think I did well, and I'm very happy how I played."
Federer took control of his semi-final early, breaking Shapovalov in the third game as his young opponent shanked a backhand.
The Swiss, who won his 100th title earlier this month in Dubai, broke again in the third game of the second set and served his way into the final against Isner, who is yet to drop a set in the tournament this year.
Auger-Aliassime is the youngest-ever male semi-finalist in Miami and only the second qualifier to reach the last four, after Guillermo Canas reached the same stage in 2007 before losing to Novak Djokovic in the final.
Despite his defeat, he will see his ranking jump from No. 55 to 33 in the world next week.
"I did the best I could," he said. "But they are chances you can't miss. It was nerves. I couldn't get a second serve in. It's tough to take."
Isner, 15 years older and 15cm taller than his rival, had only been broken twice in 48 service games at Miami and it was not long before the youngster realised what makes his booming serve so difficult to break down.
A golden opportunity arose at 2-3 only for Isner to save three break points, but Auger-Aliassime regrouped and managed to finally lead 4-3.
But the Canadian double-faulted while attempting to serve for the set and in the tie-breaker, the world No. 9 kept the pressure on.
Auger-Aliassime was unable to hold at 4-3 and that gave Isner the platform to seal the first set.
In the second set, a brilliant backhand winner set up another break chance and when Isner hit long, the Canadian moved 4-2 ahead and superbly held with an ace to extend his advantage.
But serving to level the match, the Canadian surrendered his third double fault and when he netted an straightforward volley, the match was back on serve and destined for another tie-breaker.
A final ace extended Isner's unblemished tie-breaker record for the event and ended Auger-Aliassime's career record against top-20 opponents, which was 5-0 entering the match.