California - Former world number one Jelena Jankovic reached the semi-finals of the BNP Paribas Open Thursday with a battling straight-sets victory over Alisa Kleybanova.
Serbia's Jankovic, the sixth seed, downed the Russian 6-4, 6-4 to set up a semi-final clash with eighth-seeded Australian Samantha Stosur.
Stosur defeated Spain's Maria Jose Martinez Sanchez 6-3, 7-6 (9/7).
By reaching the semi-finals, Stosur is projected to move from her current career high of 11th in the world rankings into the top 10 next week.
Stosur has reached the final four without dropping a set. In the fourth round she ousted defending champion Vera Zvonareva of Russia.
Stosur wrapped up the victory amid some confusion on her fourth match point, when Martinez Sanchez finished with a double fault.
The Spaniard's first serve had been called good and but was ruled wide on a replay after Stosur challenged - but not before swiping a return that landed out.
Apparently, both the umpire and Martinez Sanchez first thought Stosur was challenging the call on her return.
"I thought the serve was a fault," Stosur said. "As soon as the ball came off my racquet I tried to challenge her serve."
After an exchange with the umpire, Martinez Sanchez went back to the baseline, then blasted another fault.
She then stood at the baseline for some moments, as Stosur walked toward the net. Martinez Sanchez said later she had somehow lost track of the tiebreak score and hadn't realized it was match point.
"It was a confusion," she said.
Stosur had taken a 6-3 lead in the tiebreaker with a crisp forehand winner, but wasted two chances to wrap it up on her own serve. After saving a third match point on her own serve, Martinez Sanchez earned a set point but couldn't convert.
Jankovic is in the semi-finals for the second time in nine appearances. In 2008 she fell in the semis to compatriot Ana Ivanovic, who went on to win the title.
Kleybanova, ranked 27th in the world, gained the first break of the second set for a 4-2 lead, but she gave it back in the next game.
Jankovic came up with solid service game when she needed it - holding at love to level the set at 4-4 as she won the last four games of the match.
Jankovic, owner of 11 WTA titles, has played sparingly this year and hadn't made it past the third round.
"I think every win that I'm getting gives me a lot of confidence," Jankovic said. "I feel that I'm coming back, and my game is getting better and better.
"It's nice to get that feeling back, the satisfaction you feel after you win a match, after you fought very hard and beat a tough opponent."