INDIAN WELLS, Calif. -- Cracking winners off his forehand in key moments, Juan Martin del Potro defeated top-ranked Novak Djokovic 4-6, 6-4, 6-4 in the semifinals of the BNP Paribas Open on Saturday, handing the Serb his first loss in 21 matches dating to last October.
Del Potro snapped his own four-match skid against Djokovic, who had beaten the Argentine in eight of 10 career meetings.
"I'm trying to hit hard with my forehands. When I have the chance to come to the net, I did all the time," he said. "I was just focusing to put in my first serve and move to my forehands, trying to make winners."
Del Potro's 133-mph ace closed out the nearly 3-hour match featuring nine breaks of serve in 96-degree heat. He raised both arms in celebration and Djokovic hugged him at the net.
Del Potro, the second Argentine to reach the final here, will play Rafael Nadal for the title on Sunday. They each have three wins against each other on hard courts.
"When you play the top guys, they are the favorites, but I will try to do my game like just like today and then see if Rafa give me a little chance to win," del Potro said.
At times, the unseasonable heat seemed to have worn down del Potro, who draped a white towel packed with ice around his shoulders on changeovers, his chest heaving from several long rallies.
Del Potro was coming off a three-set win over Andy Murray in similarly hot conditions in Friday's quarterfinals.
The heat -- nearly 20 degrees above the average of 78 -- also affected Djokovic, as did the shadows that eventually overtook the court as the afternoon wore on. He blew a 3-0 lead in the final set, and from there, del Potro won six of the last seven games.
Djokovic attributed del Potro's dramatic turnaround to "his fighting spirit and my lack of concentration.
"I didn't deserve to win. Whenever I had chances, second, third set, I throw them away with some unforced errors. My movement was poor, and I congratulate my opponent," he said.
It was Djokovic's first loss since Oct. 31, when American Sam Querrey beat him indoors at the Paris Masters. The Serb had won 17 consecutive matches and two titles, including the Australian Open, to start the year.
It was Djokovic's second-longest winning streak of his career. Against top-10 players, he had won 14 in a row since losing to Murray in last year's U.S. Open final.
"He deserved to win because he was more composed in the important moments and he played the right shots," Djokovic said about the seventh-ranked del Potro. "He stepped into the court, where on the other side, I made a lot of unforced errors and was at back of the court too passive."
Del Potro had 25 winners, 34 unforced errors and saved 7 of 11 break points.
Nadal rallied to beat Tomas Berdych 6-4, 7-5 in the other semi and reach his fourth ATP Tour final in as many events.
Off to the best start of his career, Nadal improved to 16-1 -- including 13 wins in a row -- on the year, having won two clay-court titles and been runner-up in another since returning from a left knee injury that idled him for seven months.
"It's very, very difficult to imagine something like this. But here we are today, and very happy about all what happened the last month, especially last three weeks," said Nadal, who beat No. 2 Roger Federer in straight sets in the quarterfinals.
"I don't have nothing to lose after seven months. I did much more than what I dreamed."
It was Nadal's 12th straight win over Berdych, including seven consecutive on hard courts.
"He looks strong again," Berdych said of Nadal, whose leg is taped just below his left knee. "He still play very aggressive, and what he was missing in his first matches when he come back after the injury was maybe a bit of confidence in his game, but definitely not today and not anymore."
Berdych came in with 18 match wins -- second-most on tour this year -- and was trying to make the final of three tournaments in a row for the first time in his career.
Berdych got broken at 5-all in the second set when he lost an easy smash in the sun, sending it wide.
Trailing 6-5, the sixth-seeded Czech held three break points, but couldn't convert. Twice Nadal came up with big serves and then Berdych committed an unforced error.
Berdych's netted forehand set up Nadal's first match point, but the fifth-seeded Spaniard pulled a forehand wide for deuce. Berdych sent a backhand into the net for Nadal's second match point, and he closed out the nearly 2-hour match in unseasonably hot temperatures when Berdych netted another backhand.
"I was very nervous at the end of the match to close the match and was lucky that my serve worked amazing in the last game in important moments," he said. "Victories like today, like the other day, helps you a lot for the confidence and to remember all the things that you have to do in every moment."
Nadal had 16 winners and 25 unforced errors but he saved 3 of 4 break points, getting broken in the eighth game on a double fault to give Berdych a 5-3 lead. Nadal then won the final three games of the match.
"When it was 5-3 since that time I serve only one first serve and he serve only one second serve," Berdych said. "Actually, that was the difference."
The only Masters 1000 doubles titles the Bryans hadn't won were at Indian Wells and Shanghai. The victory extends their record for most doubles titles as a team to 86. It was their fourth title of the year, including the Australian Open.