INDIAN WELLS - Hard-serving American John Isner's remarkable run continued as he stunned world No. 1 Novak Djokovic to book an Indian Wells final showdown with world No. 3 Roger Federer.

World number 11 Isner fired his 20th ace of the match to topple defending champion and top seed Djokovic 7-6 (9/7), 3-6, 7-6 (7/5) on Saturday. Federer then used an ace on match point to seal a 6-3, 6-4 victory over world number two Rafael Nadal as the two renewed their epic rivalry with their first meeting at the Indian Wells Masters. Isner's first victory over a world number one ensures he will move into the top 10 in the world rankings for the first time. "Not many people can say they've ever beaten the No. 1 player in the world," said the 26-year-old American Isner. "I'll always be able to say that.

"I'm just going to keep on riding this wave I'm on and see how far it can take me." For Djokovic, 24, it marked a second straight semi-final defeat after he fell at the same stage in Dubai to Andy Murray earlier this month. Reigning Australian Open champ Djokovic is now 14-2 on the season. "It's frustrating when somebody serves over 70 percent of the first serves in and with that angle and with that speed and accuracy," Djokovic said. "But I played him before. I knew I had to stay patient and just wait for the chance. I had some chances. I didn't use them." Isner closed the two hour, 45 minute match out with his 20th ace in front of a crowd of about 15,000.

Djokovic, who saved a match point in the 12th game of the third set to force the tiebreaker and saved two match points on his own serve in the final tiebreaker before Isner closed it out, finished with eight aces and two double faults.

"That's why I play this game, to be able to enjoy moments like that," Isner said. "The stadium was packed, there wasn't an empty seat in the house, and everyone was on their feet. Cheering for me, too. It was very special when that last ball went by him and I knew I had won the match. It was a weird feeling, a very nice feeling. It's something that you don't experience every day. So I was just trying to take it all in."

One of the sport's great rivalries was on display in the second semi-final between 16-time Grand Slam winner Federer and reigning French Open champ Nadal which started three and a half hours late and was played in difficult windy and rainy conditions.

"I had a good day. It was a great match in tough conditions," Federer said. "It was so difficult but man I couldn't be more happy. I played amazing. We both expected rain, and it did rain a few times." Federer even had a few extra minutes to think about what turned out to be his final ace after officials pulled the players off the court because of rain just as he held match point leading 5-4 and 40-30.

He returned a few moments later and hammered the final nail in the coffin – a 125 mph ace that ended the one hour, 31 minute match. "I thought about going down the 'T' but when I was tossing the ball in the air I thought I would go the other way," he said. Nadal and Federer had met 27 times previously but never before on the hardcourts at the Indian Wells Tennis Garden. Nadal has the edge over his Swiss foe having won 18 times, including four of the last six.

This marks their second meeting this year after Nadal beat Federer in the semi-finals at the Australian Open. Nadal said he couldn't overcome Federer's quick start Saturday and then the wind and rain on centre court troubled him. "He started the match playing unbelievable," Nadal said. "At the beginning it wasn't windy and I was able to play with some tactics. But later the crazy wind started and it was difficult for me to play."