MELBOURNE, Jan. 17 (Xinhua) -- A record fifth set battle on the outside courts capped off an already astonishing opening round of the Australian Open on Tuesday as the men's top seeds continue their quest for glory.
Croatian Ivo Karlovic is feeling aches and pains in his knee and back after smashing a record 75 aces in the five hour and 15 minute clash that culminated in a 157-minute fifth set battle against Argentine world No. 68 Horacio Zeballos where no point had a rally beyond three hits.
Karlovic dug deep from two sets down in the historic 6-7 (5), 3-6, 7-5, 6-2, 22-20 win to make it the longest match (number of games) in the tie break era at the Australian Open.
"It was real difficult match," the world No. 21 told reporters, admitting he didn't want the match to end so they could beat the 11 hour and five minutes set by John Isner and Nicholas Mahut at Wimbledon in 2010.
"It was also difficult mentally because I was down 2-0, I had to also fight against him and against my own head. So it was definitely really difficult."
Plans however went more to script for the Australian Open's top seeds with Novak Djokovic's title defence on track after downing Spain's Fernando Verdasco in an at times tough straight sets (6-1, 7-6 (4), 6-2) on Tuesday night.
"I think from one perspective it was good that I got to have the very tough first-round match, because it made me prepare better and kind of approach this match and the tournament with the right intensity right from the blocks, right from the first point," the world No. 2 told reporters.
"He's a quality player, a former top 10. He beat Nadal in first round last year here. He's a big match, big-time player."
World No. 9 Rafael Nadal also took to court, dispatching Germany's Florian Mayer 6-3, 6-4, 6-4 in just over two hours as his comeback from injury continues.
The humble Spaniard told reporters the first round is never easy given there are more nerves, but the way he's playing "all the key points" is very important.
"I didn't play against an easy opponent, the way he plays is not a conventional game," Nadal told reporters.
"He changed the rhythm of the point, changing with a slice, then he hit a winner, then he play a little bit slower ball - it's not easy to read his game.
"So (I) just am happy the way I played."
In the women's draw, American superstar Serena Williams is one to watch in the later rounds after cruising to a 6-4, 6-3 victory over Switzerland's Belinda Benic who "is not disappointed" with how she played.
"I knew that I played good, but obviously it's not enough against Serena," Benic told reporters.
"It's not enough to play just, like, not bad, so you really have to bring the best."
Round two kicks off on Wednesday, with China's Peng Shuai, Duan Yingying and 20th seed Zhang Shuai all featuring against tough opponents.
Peng faces Canada's Eugenie Bouchard - former world No. 5, currently ranked 47 - on Hisense Arena late Wednesday while Duan will be on court first up against former world top 20, currently ranked No. 88, Varvara Lapchenko from the United States.
Zhang won't take any chances in a repeat of her China Open round two clash against American Alison Riske after the "very tough game" ended on a tiebreak.