Robert Somers at Melbourne Park
Top seeds Roger Federer and Novak Djokovic survived scares to progress to the last 32 at the Australian Open on Wednesday.
Djokovic held off Croatia's Ivan Dodig in four sets while Federer overcame a bigger fright, taking until the early hours of Thursday to edge out Frenchman Gilles Simon in five sets.
The Swiss Master's 6-2 6-3 4-6 4-6 6-3 victory takes him to a third round clash with 45th ranked Belgian Xavier Malisse.
The world No.2 took the first two sets in commanding style, 6-2 6-3, but Simon, who defeated Federer in their only two previous matches, was able to bounce back to take the third set with consecutive breaks of Federer's serve.
Then in the fourth Simon broke late to win 6-4 and the two players headed to the deciding set with the 16-time major champion's tournament defence in serious jeopardy.
With a packed Rod Laver Arena filled with tension, Federer then threaded a forehand down the line to break for 4-2 in the fifth set before spearing an ace into the corner from his fifth match point three games later.
Third seed Djokovic was also made to work hard before suppressing the challenge of Dodig.
Djokovic, a former champion at Melbourne Park, prevailed 7-5 6-7 (8-10) 6-0 6-2 in three hours and 21 minutes.
A break in the 12th game was enough to hand Djokovic the opening set but he was broken when serving for the second set at 5-4 and went on to lose it in a tie-break.
However world No.81 Dodig's taxing effort, particularly in the second set, sapped him of energy and he was a spent force as Djokovic lost just two games in the final two sets.
Djokovic will next confront Serb Viktor Troicki in the third round, after the 29th seed beat Frenchman Nicolas Mahut 6-4 6-2 1-6 6-3.
The night's other winners included France's Gael Monfils, who held out a stubborn Frederico Gil of Portugal 6-4 6-3 1-6 6-2 on Margaret Court Arena and Swiss world No.19 Stanislas Wawrinka eclipsed 105-ranked Bulgarian Grigor Dimitrov 7-5 6-3 6-3.
Earlier sixth seed Tomas Berdych and eighth seed Andy Roddick had easy days while ninth seed Fernando Verdasco survived a major scare before joining them in the last 32.
Berdych struggled early against the world No.35 Philipp Kohlschreiber, but regrouped to take the match 4-6 6-2 6-3 6-4 in a tick over three hours at Margaret Court Arena, while Roddick was always in control as he claimed a 7-6 (9-7) 6-2 6-3 win over Russian Igor Kunitsyn.
It was a different story for Verdasco though with the Spaniard staging a remarkable comeback to defeat unseeded Serbian Janko Tipsarevic 2-6 4-6 6-4 7-6 (7-0) 6-0 after nearly four hours on court.
Tipsarevic played like a man possessed in the opening two sets as he clubbed 34 winners and hit just 14 unforced errors compared to Verdasco's 28 and 32.
But Verdasco gradually worked his way back into the match and claimed the only break of the third set to keep his chances alive.
The Spaniard then surrendered his serve in the opening game of the fourth set to hand the initiative back to his opponent.
Tipsarevic would eventually serve for the match at 5-4 and again at 6-5, but despite having three match points, he was unable to close out the match.
Verdasco took all seven points in the tiebreaker and then conceded