WITH friends like these who needs enemies?

Viktor Troicki and Novak Djokovic are best of buddies and first hit a ball together at the age of eight or nine. They combined to help Serbia win the Davis Cup in 2010 – with Troicki winning the decisive fifth rubber in the final against France – and in a month's time they will team up to represent their nation in the Olympic doubles event. But days like this must test the relationship somewhat.

It took just 90 minutes under the Centre Court roof yesterday for the world No.1 to complete a seriously one-sided 6-3, 6-1, 6-3 victory over his countryman. That made it 12 times in a row that a meeting between the two players had resulted in the same outcome, with Troicki's only victory coming in their very first meeting on the tour, back in Umag in 2007.

There might be an occasional pang of guilt about overshadowing the life's work of the world No.34, but it is unlikely that Djokovic dwelled for too long on such matters last night. Not only had he progressed into his 13th consecutive grand slam quarter-final, he had acquired the advantage of a day's rest on his next opponent.

Florian Mayer leads Richard Gasquet by a set and 2-1, but the bizarre decision of the All England Club not to play it to a finish on Centre Court means that whoever wins that match will be playing for the third day in a row by the time they face Djokovic.

The Serb said he was relieved to have beaten the weather, and insisted "we will see" whether the circumstances hand him an advantage over his next opponent. Indeed, with further rain forecast for the next 24 hours, there are no guarantees that Mayer and Gasquet will even be able to complete their match today, which could lead to either being forced to play two matches in the same day. Djokovic declined to answer whether the schedulers would have arrived at the same conclusions if Serbia played host to a grand slam event.

"Well, I was happy that I was on the Centre Court because of the weather conditions," he said. "As I say, I cannot say it's right or wrong they didn't put it on. They know what they're doing, I guess.

"Obviously, it's good for me to finish and to have a day of practice tomorrow and get ready for the next challenge. But they say the weather forecast is not really great. I hope they can finish so we can be on time.

"I actually thought when I finished the match that they will put one match to finish or to start on the Centre Court, because they had another three hours," he added. "But they explained to me that they couldn't do that because it would be too much trouble with organising the crowds going out from the Centre Court and the new crowd coming in. It's not in my hands to say what's right or wrong. I'm sure they have lots of experience in scheduling, and they're doing a good job."

They are certainly doing a good job for him. Djokovic has now played three of his four matches under the roof, which could yet be another advantage should the rain continue to fall. The 25-year-old was comfortable enough during an imperious second set to get 92% of his first serves in play.

"There is a difference I think in the speed of the ball that travels through the air," he said. "I talked with Viktor, whose debut it was under the roof, and he said it's much slower than his previous matches. So I've kind of got used to it."

Troicki's last seven matches at grand slams had all gone to five sets, but Djokovic was in no mood for mercy. Even if it was to his best friend.

"The first match we played was at a local tournament when I was eight and he was nine years old," Djokovic said. "We are very good friends in the private life. So all these things are playing around with your emotions a little bit. But in the end we are professionals. It doesn't matter who is across the net, you want to win."