Croatia's Ivan Ljubicic became the first major casualty on the opening day of the Australian Open, falling 4-6, 7-6, 6-4, 6-4 to American Mardy Fish on Monday.
The fourth seed, a quarter-finalist in 2006 and already a winner this year at Doha, struggled to match the unerring accuracy of the world number 42, who prevailed in two hours and 53 minutes on Vodafone Arena.
Nobody served more aces in 2006 than the big-serving Ljubicic, but Fish generally returned superbly, breaking in the opening games of the third and fourth sets before going on to tie his career record against the Croatian at 1-1.
Fish, who slipped as low as 341 in the rankings last year after a series of wrist operations, will play Frenchman Nicolas Mahut in the second round at Melbourne Park.
Earlier, Marcos Baghdatis of Cyprus won the battle of former runners-up by beating Rainer Schuettler 6-4, 2-6, 6-3, 6-2.
Baghdatis, the 11th seed who lost to Roger Federer in last year's final, wore down his German opponent, who was suffering from flu and had to call a medical time out in the third set.
"I didn't feel good today and it was not a good match but I am just happy to get through," Baghdatis told a news conference.
"I am playing really well in practice but today I wasn't really there on the court. I tried to stay cool and calm and obviously Rainer was injured."
Baghdatis, 21, did not produce the inspired tennis that carried him to the final 12 months ago on a wave of popular support, but his strong all-round game was too much for Schuettler to cope with.
The German dominated the second set but, clearly hampered by illness and struggling with a leg injury, he was unable to sustain his momentum as Baghdatis moved him skilfully around the court.
Schuettler, who reached the 2003 final at Melbourne Park before losing in straight sets to Andre Agassi, called for the doctor late in the third set but his treatment failed to revitalise him and Baghdatis romped through the fourth set to complete victory in two hours 24 minutes.
"It was nice getting back here again and feeling the crowd. They were good," said Baghdatis, who will play Gael Monfils of France in the second round.