Australian Open: Ana Ivanovic ousts Jelena Jankovic in battle of thawed Serbs

Ana Ivanovic beat fellow Serb and once fierce rival Jelena Jankovic 7-5 6-3 in a battle of former world number ones to reach the fourth round of the Australian Open on Friday.

Three years ago or so, a clash between the two would have been in deep into the latter stages of a grand slam, rather than a third-round meeting. Former French Open champion Ivanovic is seeded 13th this year and Jankovic at 22 but despite their fall from the top of the women's game, their rivalry remains intense.

"It's competitiveness, said Ivanovic, who will next face fourth seed Agnieszka Radwanska after the Pole took her winning streak to 12 matches by thrashing Britain's Heather Watson. "You have that with everyone you play - and especially someone coming from your country. We were (once) both looking for the number one position and to win a grand slam.

"Of course there is going to be rivalry, but I think there is healthy rivalry too because you kind of push each other. "We played in the 2008 French Open (semi-finals) and then here we were both in the semi-finals in 2008, so it definitely brings a lot of memories. "We haven't played each other in a grand slam for a while, but it's always tough. "She's still a very good player and even though we are different opponents now than we were then, still it's a battle, and every match you want to win."

There was a time where the two would barely exchange a word but over the years their relationship has thawed, also helped by their efforts together in the Fed Cup. "We had a really good week in Prague for the final of the Fed Cup," said Ivanovic.

"We were hanging out a lot, joking. It's nice. We have known each other for a while." Ivanovic trails Radwanska 4-3 in their previous meetings, losing the last four but insisted she was playing well enough to win and knows what she needs to do to topple the fourth seed.

"Being patient is going to be a key," she said. "It's going to be tough, for sure. I have to be prepared to work hard for my points and to keep on putting pressure on her. "She definitely matured a lot as a player. She was always a very tough competitor. She has a style of game that she doesn't give you much and you really have to work for your points."

Ivanovic has lost some weight in recent months and says she is still trying to strike the right balance between fleetness of foot and power. "It's just about the muscle and just getting the right balance because still you need to feel light on the court but you have to be powerful," she said.

"I had a really tough match the other day and today I came out and I was feeling fine and was explosive - so I'm very, very pleased that it's paying off. But I'm still working at it."