Isner will play either No. 2 Rafael Nadal or No. 3 Roger Federer in Sunday's final. They were to play for the 28th time but the first at Indian Wells in the other semifinal, although rain began falling shortly after Isner left the court on a cool, cloudy day at the Indian Wells Tennis Garden.
Victoria Azarenka and Maria Sharapova will meet for the women's title Sunday.
Isner's victory guaranteed he will break into the top 10 for the first time in next week's ATP Tour rankings at No. 10. A victory in the final would move the American to No. 8, passing countryman Mardy Fish, who is currently in that spot.
Isner needed nearly three hours to reach his first ATP Masters 1000 series final after 25 tries. He didn't get past the round of 16 in his first 23 events until making his first semifinal in Paris last fall and now the final in the desert.
Isner threw his arms up and soaked in the applause from the crowd that was squarely behind him throughout the match.
The 6-foot-9 American towered 7 inches over Djokovic, giving Isner an easy advantage with his serve-and-volley game. He played a few loose points in the 12th game of the final set, sending a forehand past the baseline on his first match point, and Djokovic held to force the second tiebreaker.
Isner aced Djokovic with a 143-mph serve to lead 3-2, then hit a forehand winner down the line to go up 4-2. Isner's 144-mph serve forced Djokovic into a netted return that set up Isner's second match point. Djokovic served up a rare ace of his own and Isner committed an unforced error before closing it out with his 20th ace.
Isner's height and power had him tabbed as a future American star since he turned pro in 2007, but success has come in fits and starts. He reached his current -- and best -- career ranking of 11th just last month, when he notched his previous biggest win over Federer in a Davis Cup match on the Swiss star's home turf.
There was a win over Andy Roddick at the 2009 U.S. Open, but casual fans may know him best for a marathon win over Nicolas Mahut at Wimbledon in 2010. They played the longest ever pro match, stretching 11 hours and 5 minutes over three days.
Djokovic, the defending champion, fell to 14-2 this season, having lost to Andy Murray in Dubai earlier this month.
Copyright 2012 by The Associated Press
