INDIAN WELLS: Jelena Jankovic had to fight her way into the fourth round of the Indian Wells WTA tournament on Monday while former world number one Kim Clijsters was upset by Russian Alisa Kleybanova.

Serbian sixth seed Jankovic beat Italian Sara Errani 2-6 7-6 6-4 in an error-strewn marathon on the stadium court before twice champion Clijsters of Belgium tumbled out 6-4 1-6 7-6.

Third seed Victoria Azarenka of Belarus also made a premature exit, going down 7-6 6-2 at the hands of 28th-seeded Maria Jose Martinez Sanchez of Spain.

Jankovic piled up 57 unforced errors, compared to Errani's 42, to clinch victory in two hours, 48 minutes when the Italian made a hash of an overhead smash after a protracted rally.

"It was really a battle out there, and I just tried to stay positive as much as I could," Jankovic, a semi-finalist here in 2008, told reporters. "I just tried to fight for every point and kept going and kept going.

"I would play a couple of points well and then I would just give away a lot of points. At the end, I was able to win and that's the most important thing."

Errani, bidding to beat a top-10 player for the first time in 12 attempts, broke the world number nine three times to sweep through the opening set in just 31 minutes.

Jankovic squandered a 3-1 lead in the second, along with five set points in the tiebreak, but leveled the match with a crunching forehand winner down the line.

The final set was also an up-and-down affair with Errani being broken three times and Jankovic twice but the Serb made her greater experience count.