By Mitch Phillips
LONDON (Reuters) - The untroubled advance of the heavy hitters in the men's and women's game continued apace at Wimbledon on Thursday as Roger Federer, Andy Murray and Petra Kvitova cruised into the third round with straight-sets victories.
The early exits of women's third seed Simona Halep and number seven Ana Ivanovic and the injury withdrawal of men's number five Kei Nishikori have been the only blips in an otherwise untroubled march to the third round for the big guns.
Murray led the way as he polished off Dutchman Robin Haase 6-1 6-1 6-4 in 87 minutes with barely a misplaced shot.
"I think in grand slams you have to try to conserve energy when you can really because the two weeks can be quite draining physically and mentally," Murray told reporters.
"If you can get yourself off the court quickly, capitalize if your opponent maybe isn't playing as well, if you're on your game, try to push yourself to keep playing that way. It can pay off toward the end of the tournament."
Federer was equally untroubled in a 6-4 6-2 6-2 mauling of American Sam Querrey.
Seeking a record eighth Wimbledon singles title, Federer was on cruise control from the off.
When he did find himself out of position he managed to manufacture a lob from between his legs that climbed over his 6ft 6ins (1.98m) opponent.
"I'm very happy with the way I played the first two matches," Federer said. "I guess there's also a little bit of relief that I'm also playing well at Wimbledon."
Possibly even more impressive was Kvitova, whose 6-2 6-0 demolition of Kurumi Nara meant the defending champion has dropped only three games in two matches.
After almost four full days of action the top four men's seeds have yet to drop a set between them, with only two going as far as a tiebreak.
It is a similar story on the women's side -- Halep apart -- as the top three and number five Caroline Wozniacki, who advanced on Thursday, have also not dropped a set.
There are still threats floating in the draw, however, and Germany's Sabine Lisicki, runner-up two years ago and with a great Wimbledon record, is one of them.
Seeded 18th, she delivered an impressive comeback win over American Christina McHale.
Lisicki lost the first set and was broken in the opening game of the second but regrouped impressively and by the end was pounding down a succession of powerful winners en route to a 2-6 7-5 6-1 victory.
Matches on the outside courts started late after early drizzle following three days of sunshine and record temperatures.
It soon cleared, however, leaving the players to deal with draining, humid conditions.
Among those involved in later matches was Rafa Nadal, who faced an awkward Centre Court test against unconventional German Dustin Brown.
(Editing by Ed Osmond)