MIAMI, FL, USA - She looked down and out, but four-time Grand Slam champ Kim Clijsters just wouldn't stop fighting, and on Tuesday pulled off one of the biggest comebacks on the WTA in recent memory, saving five match points to beat Ana Ivanovic in a fourth rounder at the Sony Ericsson Open.

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Clijsters was a heavy on-paper favorite in the match, seeded No.2 to Ivanovic's No.19 and dropping only seven games in the pair's three previous meetings combined. But this time would not be anywhere near as straightforward.

Although she lost the first set in a tie-break, Ivanovic was clearly asserting herself against Clijsters for the first time in her career. She won five of the next six games after that breaker and eventually took the second set, 6-3, and again won five of six games to go up 5-1 in the third. That game also brought match points, as the No.2-ranked Clijsters got down 0-40 on her serve.

That's when the turnaround took place. Clijsters saved those three match points and another one at ad-out, holding serve for 2-5. She faced a fifth match point serving at 3-5 but saved that, too. The Belgian just wouldn't let go of the title she won for the second time last year, eventually clawing out a 76(4) 36 76(5) win.

"Even if it's 5-1, you start a game at 0-0. Your opponent has to win four points," Clijsters said. "You just try to work your way back into it. When you feel your opponent starts to be a little less aggressive and makes a few more mistakes, or looks at the sideline a little bit more, you noticed those things.

"That's what made me think there was still a little chance."

Despite the end result, Clijsters was still impressed with the level from Ivanovic. "She was playing really well. It has been a long time since I've seen her play like that. Ana is very tough to beat if she can play like that and keep it up."

Ivanovic was understandably disappointed afterwards but showed her funny side in press when asked if it was hard to accept. "It's very hard, yeah - you should see my racquet," the Serb said. "But I felt like I did nothing wrong. I had my opportunities and she played some really good tennis. I fought hard and stayed with her the whole match. I'm of course disappointed but there are positives."

Ivanovic, a former No.1, was also very complimentary towards the Belgian. "I think no matter what the rankings say, she's the hottest player at the moment."

Towards the end of her press conference, Ivanovic described exactly what happened to the racquet. "I kind of broke my racquet, then kind of cried a little bit. And then I was okay," the 23-year-old said with a smile.

Awaiting Clijsters in the quarterfinals will be No.8-seeded Victoria Azarenka. Clijsters leads Azarenka in their head-to-head, 4-1, and in their only meeting this year was an easy winner, beating the Belarusian in Sydney, 63 62.

Japanese No.1 Kimiko Date-Krumm has set up a personal fund called Always Smile to help the Japanese earthquake and tsunami victims. If you would like to help out, please visit http://www.kimiko-date.com/gien/index.html.