Melbourne :Reigning champion Roger Federer was taken to five gripping sets by French nemesis Gilles Simon on Wednesday before scraping into the Australian Open's third round.
The world number two, defending his only remaining Grand Slam crown, was pegged back from two sets up before scoring his first-ever win over Simon, 6-2, 6-3, 4-6, 4-6, 6-3, to stay on course for his fifth Open title.
It was a desperately close call for the 29-year-old, who holds a record 16 Grand Slam titles and only narrowly avoided his worst performance at a major in eight years, and his poorest ever Australian Open outing.
"Today I got lucky to go through," a relieved Federer said.
"He's a great player. Matches against him don't come easy and they always go the distance. Hopefully I won't play him any more!" he laughed.
Federer had lost both his previous matches in 2008 with Simon, who remains one of only three active players -- along with Rafael Nadal and Britain's Andy Murray -- with a winning record against the all-time Grand Slam record-holder.
The Swiss was powerless against Simon's laser-guided groundstrokes in the third and fourth sets but recovered to find the crucial break with his famous forehand and aced the fifth match point after huge tension at Rod Laver Arena.
Federer is bidding to become only the second man to win five Australian Opens after six-time champion Roy Emerson, and thwart arch-rival Nadal's bid to unite all four Grand Slam titles for the first time in 42 years.
Serbian third seed Novak Djokovic also had difficulties in his ethnically- charged clash with Croatia's Ivan Dodig. Djokovic, who won his only major title here in 2008, let slip a set before winning 7-5, 6-7 (8/10), 6-0, 6-2.
The match was played under a heavy security presence but there was no repeat of violence between ethnic Serbian and Croatian fans which has repeatedly hit the season's first Grand Slam.
Earlier Venus Williams bravely battled through a painful muscle strain to reach the third round, women's top seed Caroline Wozniacki finally hit form and Spain's Fernando Verdasco survived another five-set thriller.
Injury-hit Williams' first tournament since the US Open looked to have ended in disaster as she screamed and clutched herself in pain when losing the first set's decisive point against Czech Sandra Zahlavova.
The 30-year-old limped off for treatment and looked uncomfortable when she returned with her right thigh strapped. But the seven-time Grand Slam winner was quickly in the points and saw Zahlavova off 6-7 (6/8), 6-0, 6-4.
"I don't know what happened," Williams said of her amazing recovery. "I started going for my shots and she wasn't as composed as before -- you have to able to play under all circumstances."
French Open champion Francesca Schiavone needed a 16-game third set before seeing off Canada's Rebecca Marino 6-3, 5-7, 9-7, while Russian glamour girl Maria Sharapova beat France's Virginie Razzano.
Meanwhile Verdasco, on the losing end of the Australian Open's longest-ever match two years ago, prevailed in five sets against Serbia's Janko Tipsarevic 2-6, 4-6, 6-4, 7-6 (7/0), 6-0.
The encounter clocked in at just under four hours, recalling his record 5hr 14min epic against Rafael Nadal in the 2009 semi-finals.
Elsewhere America's Andy Roddick, 28, downed Igor Kunitsyn of Russia 7-6 (9/7), 6-2, 6-3 and Czech sixth seed Tomas Berdych beat Germany's Philipp Kohlschreiber in four.
Denmark's Wozniacki, 20, shook off a troubled start to the year with a 6-1, 6-0 demolition of America's Vania King, burying 23 winners to reach the third round and join a list of impressive women's winners.
Belgium's Justine Henin won 6-1, 6-3 against Briton Elena Baltacha and Russia's Svetlana Kuznetsova beat Arantxa Rus 6-1, 6-4. Yesterday, favourite Kim Clijsters had humiliated former finalist Dinara Safina 6-0, 6-0.