Rafael Nadal had his fans drooling with another muscle-bulging display of brilliance to crush Ryan Sweeting 6-3, 6-2, 6-4 on Wednesday and stay firmly on course to defend his Wimbledon title.

With rain in the air and the roof closed, wolf whistles echoed around Centre Court when the Spaniard changed his shirt and gasps of awe met his most effortless winners in a one-sided second-round match.

"It was a new experience for me (under the roof), a good experience. But the tournament is outdoor, not indoor, and I prefer to play outdoor," Nadal told a news conference.

"I don't know if because of this change the atmosphere inside the court with the roof is more humid or because it was raining before the match or something. But seems like the court is a little more slippery than usual."

Despite slight trepidation under the roof, the champion barely sent a forehand long or wide throughout the encounter, -- even when under pressure -- and his rampant serves and pinpoint volleys were equally impressive.

Nadal had started the French Open in nervous fashion last month before gradually improving and peaking in time to beat Roger Federer yet again in the final.

In contrast, he has found his groove straight away at Wimbledon and the prospect of him playing still better next week would frighten even the most avid supporter of Federer, Novak Djokovic or Andy Murray.

He next takes on Gilles Muller, a man who beat him at Wimbledon in 2005, but Nadal is feeling so confident again that he sharply dealt with a question about whether he is in decline following a slightly shaky first half of the year.

"Maybe. But I won Roland Garros two weeks ago. I don't forget," the Mallorcan smirked.

"Gilles is a very dangerous player. He has a very good serve, good volley. He's especially a very dangerous player on this kind of surface."

Vera Zvonareva survived a scrappy second set to slip into the third round of Wimbledon with a 6-1, 7-6 win over fellow Russian Elena Vesnina on Wednesday.

The second seed, runner-up to Serena Williams 12 months ago, appeared to be cruising to an easy win on a sun-bathed Court Two but her she inexplicably lost rhythm on her serve in the second set as the players kept on trading breaks.

The 26-year-old, whose only defeat to Vesnina in six previous meetings was when she was forced to retire with an ankle injury, kept her cool and sealed victory when her opponent netted a service return.

Zvonareva will next face surprise 2010 semi-finalist Tsvetana Pironkova.

Home hope Andy Murray reached the third round at Wimbledon with a routine 6-3, 6-3, 7-5 win over German Tobias Kamke on Wednesday.

The fourth seed continued the fluent form which brought him the Queen's title this month, serving solidly and denying his opponent many chances to attack.

Murray, bidding to become the first British men's singles champion at Wimbledon for 75 years, broke serve to lead 6-5 in the third set and he sealed victory with a service winner on his first match point.

It was Venus's turn to write the Williams plot line at Wimbledon on Wednesday as she survived a gripping three-set battle with 40-year-old Japanese Kimiko Date-Krumm.

A day after her sister Serena sobbed after beating Aravane Rezai to open her title defence, 23rd seed Venus was made to sweat buckets under Centre Court's closed roof for a 6-7 6-3 8-6 win in just under three hours.

On Monday it was her tennis ouitfit, on Tuesday it was her emotional sister and this time it was for the 31-year-old's spellbinding duel with a veteran who soaked up everything the American could throw at her.

With play delayed on all the other courts, Williams and Date-Krumm, who on Monday became the second oldest player to win a women's singles match at Wimbledon, served up an early contender for match of the tournament.

"I thought she played unbelievable today," Williams, who returned from a five-month injury layoff at Eastbourne last week, told reporters.

"I thought she had some luck on her side, too, with net cords, balls hitting lines. I just thought today was a perfect storm for her to try to get a win.

"Thankfully I had some answers."

Date-Krumm made her Wimbledon debut in 1989 when the Williams sisters were still bashing balls about on park courts in Compton and the idea of a roof over the most famous centre court in tennis was still a pipe dream.

You have to go back to 1996 for her best Wimbledon performance when she lost to Steffi Graf in the semi-finals before taking a 12-year break from tennis.

"She hits a ball that no one else hits. I never played anyone who hits the ball like this," Williams said of the flat-hitting Japanese whose game is a throwback to days gone by.

Williams was certainly bemused as she lost her first three service games to trail 5-1. She fought back to force a tiebreak, went 6-1 down, recovered again to 6-6 but slipped behind as an inspired Date-Krumm grabbed the next two points.

Williams upped her game to level the match before moving 2-0 up in the decider. Date-Krumm began hitting the ball unerringly close to the lines, though, and worked her way back to 2-2.

At 6-6 former world number four Date-Krumm sniffed a break at 30-30 but Williams flashed a sublime backhand winner and finally sealed victory in the following game.

Three time finalist Andy Roddick comfortably advanced to the third round on Wednesday.

The American, seeded eighth, scored a comprehensive 6-4, 6-3, 6-4 win over Romania's Victor Hanescu.

Roddick has become something of a Wimbledon fixture over the last decade and fans know exactly what they are going to get when they pay to watch the American.

This year he is making his 11th successive assault on the tournament with only an outside chance of matching his three runner-up finishes in 2004, 2005 and 2009.

As a brash, young, cap-wearing American, the crowd were not quick to warm to him in his early years but three things British fans love are an underdog, a trier and a good-spirited loser. Despite his 2003 U.S. Open title and former number one ranking, they soon saw all three in Roddick.

Despite the solid support he received on Court One, Roddick said he was still unsure of how he fitted into the Wimbledon picture.

"I think a lot changes over the course of 10 or 11 years but it's tough for me to look at my relationship with the fans here objectively," he said.

"I know from my end I certainly enjoy it but I'm not going to speak for them, though they've always been great to me."

Three times he got to the final here and three times he found Roger Federer standing in his way.

Twice he was unable to make much impression on the Swiss maestro, who had also beaten him in the 2003 semi-finals, but in 2009 he came agonisingly close before eventually going down 16-14 in the fifth set of a classic encounter.