Indian Wells, California: Former champion Jelena Jankovic became the first seed to tumble out of the Indian Wells WTA tournament, losing 6-4 6-3 to American wild card Jamie Hampton in the second round on Friday.

Seeded 12th, the jet-lagged Serb who had reached the semi-finals in her last two tournaments struggled to find a rhythm as she was broken three times in the opening set and twice in the second.

World No 1 Victoria Azarenka had to work hard to extend her unbeaten record to 18-0 this year, beating Germany's Mona Barthel 6-4 6-7 7-6, while 13th-seeded Russian Anastasia Pavlyuchenkova was ousted 6-4 6-4 by American Vania King.

Wimbledon champion Petra Kvitova, however, eased into the third round of the elite event with a 6-1 6-3 demolition of fellow Czech Barbora Zahlavova Strycova.

Hampton, who made her debut in the top 100 of the rankings last week, sealed her surprise victory in just under 90 minutes when a Jankovic forehand sailed wide on the stadium court.

"It was a bad day of tennis for me," Jankovic said. "I just did not feel the ball. My legs felt so heavy on the court, so I was moving very badly out there.

‘Shadow of myself'

"Hampton played solid. She was playing very well. I was really a shadow of myself. I guess it's one of those days where you just come on the court and the legs don't go, the reactions are not there."

Jankovic reached the last four in Dubai and Kuala Lumpur in her previous two events but felt her journey from Malaysia took its toll.

"I was in good form in Dubai and Kuala Lumpur, but maybe just had not much time to get over the jet lag and feel fresh before this tournament," the former world No 1 said.

Playing against the 99th-ranked Hampton for the first time, Jankovic was broken in the second, sixth and tenth games of the match to lose the opening set in 42 minutes.

Hampton, who upset 38th-ranked Polona Hercog of Slovenia in the opening round at Indian Wells, surged into a 5-1 lead in the second set before fending off a late Jankovic fightback.

"I was pretty nervous before the match,' said Hampton, who lost in the first round on her Indian Wells debut last year.

"I didn't really know what to expect. I think the fact that I got a match under my belt here, the round before, helped me a lot."