Melbourne: Caroline Wozniacki thanked Roger Federer for roaring through his match and allowing her a decent night's sleep after she crushed local hope Anastasia Rodionova 6-2, 6-1 at the Australian Open on Monday.   

Marathon tussles in the night session at Rod Laver Arena have often left players battling away into the early hours but Federer's straight-sets defeat of qualifier Alex Kudryavtsev meant a relieved Wozniacki could complete her match well before midnight.   

"I'm not a morning person," world number one Wozniacki told reporters after silencing the home crowd with a 76-minute victory in the opening round.   

"I like to sleep. I like to sleep during the day as well. I like my naps and I feel good in the evening.   

"It's great to play the first night match because you know exactly when you're on. Roger did very well ... he always plays the points very fast and there aren't too many long rallies," the Dane added.   

Wozniacki, criticised for being number one without a grand slam title to her name, will lose the top ranking if she fails to make the fourth round here.   

She at least has no concerns about her fitness after shrugging off a wrist injury she sustained at the Sydney International warmup event.   

"It feels better. I was a bit nervous before the match," said Wozniacki. "I didn't know exactly what to expect. I'm very happy about the way I felt out there today."   

Dressed in red and oozing menace, the Dane quickly broke her 103rd-ranked opponent's serve and then her spirit as she bullied her from the baseline.   

Rodionova cursed and muttered throughout but permitted herself a wry smile as ironic cheers rang out when she held serve to trail 5-1 in the second set.   

That proved, however, a brief delay in Wozniacki's march as she served out for victory in the next game, sealing it when the Australian hit the ball long on match-point.