Last month during the SAP Open in San Jose, Andy Roddick said John Isner has "the biggest weapon in the game."
Roddick was referring, of course, to the 6-foot-9 Isner's devastating serve.
Isner will need it, and more, when he faces top-ranked and defending champion Novak Djokovic on Saturday in the semifinals of the BNP Paribas Open at Indian Wells.
Isner, ranked and seeded 11th, outlasted 13th-seeded Gilles Simon of France 6-3, 1-6, 7-5 Thursday night to reach his second ATP World Tour Masters 1000 final four.
Djokovic, who has won the last three Grand Slam titles and four of the last five, advanced with a 6-3, 6-4 victory over 12th-seeded Nicolas Almagro of Spain.
Isner, 26, is 0-2 against Djokovic, 24. In 2010, Djokovic won 6-4 in the fifth set in the first round of the Davis Cup on clay in Serbia and 7-6 (1), 6-2 in the semifinals at Beijing on hardcourt.
"To beat that guy, you have to be on top of your game no matter who you are," Isner told reporters. The same goes for me. I'm going to have to obviously serve well and take my chances after that.
"So it's going be one of the toughest matches I'll ever play, because he's No. 1 in the world. I have a day to kind of sit on it. I have doubles (Friday). But hopefully I'll come out on Saturday and put together a good match and take it to him as best I can."
Isner, who won a 2007 Futures title in the Sacramento suburb of Shingle Springs in his pro debut, is bidding to become the first American man to win the Indian Wells title since Andre Agassi in 2001.
In a quarterfinal battle of Marias from Russia, second-seeded Maria Sharapova overcame a 6-3, 2-0 deficit to subdue No. 20 Maria Kirilenko 3-6, 7-5, 6-2.
Sharapova will meet 15th-seeded Ana Ivanovic, who eliminated No. 7 Marion Bartoli of France 6-3, 6-4, in the semifinals. Both Sharapova and Ivanovic have been ranked No. 1 and won Indian Wells.
Bartoli, last year's runner-up to Caroline Wozniacki, summoned a doctor early in the second set. After the match, she said she began feeling sick Wednesday night and suspected she has the same virus that has afflicted many other players and fans this week.