Ivanovic beat Azarenka for the second time this year
Ana Ivanovic enjoyed a much-needed boost with a 2-6 7-6 (8-6) 6-2 victory over ninth seed Victoria Azarenka in the first round of the Cincinnati Open.
Ivanovic, a former world number one, has slipped to 62nd in the world because of injuries and poor form and has made just two semi-finals in 2010.
But the 22-year-old came back from 6-2 5-3 down to beat the in-form Azarenka.
Russia's Dinara Safina joined the Serb in the second round with a 7-5 6-4 win over Roberta Vinca.
Safina, who has also been battling injury, will now face Kim Clijsters.
Clijsters, seeded fourth, had a first round bye but the US Open Champion is yet to play a competitive singles match since reaching the quarter-finals at Wimbledon in June.
"It's been a while," said the Belgian. "I'm looking forward to playing a match. It doesn't matter who I play."
Ivanovic had been distraught after a first-round defeat by Shahar Peer in San Diego last week and she looked set for another early exit when Azarenka served for the match on Monday night.
But the 2008 French Open champion, who also beat Azarenka on her way to the semi-finals in Rome in May, fought back to set up a second-round clash with Yaroslava Shvedova.
"The crowd helped me so much,"
Ivanovic told the WTA website.
"It was so great to see a lot of young kids.
"It's my biggest win since Rome. Rome was a great week for me, but this victory means a lot.
She just came off a title,
but also the way the match was progressing, the last few weeks I was losing matches like this.
"It's good to see that hanging in there gives the good results."
World number two Jelena Jankovic is looking forward to her first match in Cincinnati after being given a bye into the second round.
And the 25-year-old Serb, who has been dogged with an ankle injury since mid-July, believes she is back to full fitness.
"My ankle's OK," said Jankovic. "I've been able to practice the last couple of days. Now it's feeling good. I'm looking forward to getting back to playing."
Jankovic will face qualifier Vera Dushevina, who beat Anastasia Rodionova 6-2 7-6 (9-7).