Australian Open, Melbourne
Venue: Melbourne Park Dates: 17-30 January
Coverage: Watch on BBC TV, Red Button, BBC Sport website (UK only) & Eurosport; listen on BBC 5 live sports extra and online; text commentary online;
Zvonareva is bidding to win her first Grand Slam title
Vera Zvonareva and Kim Clijsters both came through tough encounters to reach round four of the Australian Open.
Second seed Zvonareva was twice broken when serving for the match against Lucie Safarova but won 6-3 7-6 (11-9).
Clijsters, seeded third, battled to a 7-6 (7-3) 6-3 victory over Alize Cornet after a tense opening set.
Agnieszka Radwanska thrashed Simona Halep 6-1 6-2 but Nadia Petrova and Shahar Peer lost, while fellow seed Sam Stosur was beaten by Petra Kvitova.
Zvonareva was matched stroke for stroke by Safarova in the early stages before breaking serve for a 4-2 lead and soon serving out the opening set.
Czech 31st seed Safarova hinted at a swift riposte when she engineered two break points in the game two of the second set, but Zvonareva saved both before holding serve with a stunning backhand pass.
The world number two maintained her momentum by breaking for a 2-1 lead and at that stage it seemed as though she would ease home.
Safarova continued to battle hard and levelled at 4-4, only to spoil all her hard work when she immediately dropped serve once more as Zvonareva edged to within a game of victory.
But she could not see it out, a further three breaks of serve taking the set to a tie-break in which Safarova wasted set points at 6-5 and 9-8. In between, Zvonareva squandered two match points.
The key point came at 9-9 when a Zvonareva backhand was initially called out, only to be ruled in after a Hawkeye challenge.
And there was no slip-up third time round as the Wimbledon and US Open runner-up induced an error from Safarova to seal her win.
"Lucie is a great player and I had to hang in there and fight for every point," said Zvonareva of her former doubles partner.
"It was a very good match for me and I am happy to be through to the next round."
Standing between Zvonareva and a place in the quarter-finals is another Czech, Iveta Benesova, who shocked 16th seed Anastasia Pavlyuchenkova.
Clijsters made hard work of her meeting with Cornet, committing 41 unforced errors, including six double faults, in a match featuring seven breaks of serve.
The first of those came in the opening game and helped Clijsters into a 3-1 lead, but the Belgian was broken in the fifth game and also let slip a 5-3 lead.
However, Cornet was unable to take advantage of the situation and crumbled in the tie-break, losing the first five points as Clijsters eventually took the opening set after 54 minutes.
Cornet showed some fighting spirit in the second set and saved two match points in the eighth game, but Clijsters then served out to complete an unconvincing win.
There was a far more comfortable passage for 12th seed Radwanska, who demolished Simona Halep 6-1 6-2 to set up a meeting with Shuai Peng.
The unseeded Chinese player edged out Ayumi Morita 6-1 3-6 6-3 despite suffering cramp late in the contest.
"I was really trying to fight," said Peng. "I just told myself not to think about the cramping."
But there were exits for 10th seed Peer of Israel and Russian 13th seed Nadia Petrova.
Peer fell 3-6 7-6 (7-3) 6-4 to 22nd seed Flavia Pennetta while Petrova, who sent Clijsters crashing at the same stage last year, was beaten 6-2 3-6 8-6 by unseeded compatriot Ekaterina Makarova.
And Czech player Kvitova ended hopes of a local women's winner when she downed Australian fifth seed Stosur 7-6 (7/5) 6-3.
"I'm obviously very disappointed not to win," said Stosur.
"But I actually thought I played really well. I don't really know how I lost it, to be honest.
"I felt like I started playing a bit better and was probably on top of her and then all of a sudden it was gone and I was a set down.
"I thought she played extremely well pretty much the whole way through. I think it was a match of a point here and a point there and she got the ones that really mattered.
"It's a tough loss, but I think I can walk off thinking I played quite well and did everything that I could."