By Nick Mulvenney
MELBOURNE, Jan 18 (Reuters) - A welcome wind blew away the stifling heat at Melbourne Park on Friday but there was no diverting Novak Djokovic from his path to a third straight Australian Open title as he marched into the fourth round without giving up a set.
Playing with the roof closed on Rod Laver Arena because of a few drops of rain that accompanied the cooler weather, Djokovic's 6-4 6-3 7-5 victory over Radek Stepanek was by no means a cakewalk, however.
The 34-year-old Czech is nobody's mug and the world number one had to work for every point in the 142-minute encounter, getting a good workout, particularly at the net, before sealing the win with a forehand pass.
"Always great to play Radek. He's very experienced, very tricky to play. Hope you enjoyed as much as we did on the court," said 25-year-old Serbian after he reached the fourth round for the seventh year in a row.
Pole Agnieszka Radwanska also continued her red-hot start to the year, notching up win number 12 with a 6-3 6-1 victory over Britain's Heather Watson in their third round tie.
The fourth seed claims she is not superstitious, which might be a good thing as she will look to extend that run to 13 successive wins in the fourth round against 13th seed Ana Ivanovic.
"I just hope I keep going," last year's Wimbledon finallist told reporters. "Of course now it is going to be harder and harder playing against seeded players."
Former French Open champion Ivanovic won the battle of the Serbian former world number ones against Jelena Jankovic 7-5 6-3 before saying that their fierce rivalry was still intense.
"You have that with everyone you play - and especially someone coming from your country," she said. "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."
Another former French Open champion, Li Na, also progressed as China's last representative in Melbourne, setting up a fourth round match against German Julia Goerges with a 6-4 6-1 victory over Sorana Cirstea.
Li reached the final in 2011 and will fancy her chances of going deep again this year, especially in the absence of the retired Kim Clijsters, who beat her in her last two appearances at the year's first grand slam.
"It was pretty good today," the sixth seed said. "I was feeling even more control again on the court. It was much easier than I thought it would be."
The number of Americans and the number of teenagers in the women's draw were both reduced by one when Madison Keys was knocked out by German fifth seed Angelique Kerber in the opening match on Rod Laver Arena.
"I'm taking away some positives. But right now, it kind of sucks," the 17-year-old said after her 6-2 7-5 defeat. "I think it was the occasion, centre court the first time. I think I almost psyched myself out."
Keys was one of five American women to make the third round and was proud of her part in the renaissance.
"I think this is probably the best America's done in a grand slam in a long time ... I think that if we keep working hard we can have better results," she said.
Venus Williams will face a severe test to become the first American into the fourth round in the first match of the evening session on Rod Laver Arena in her much-anticipated encounter with second seed Maria Sharapova.
The last standing American in the men's draw, Sam Querrey, is also on court against Swiss Stanislas Wawrinka to decide who will meet Djokovic in the next round. (Editing by Alastair Himmer)