Roger Federer pleaded with Grand Slams not to be panicked into reducing matches to best-of-three sets after injured players were accused of taking the money and running on Tuesday.

Federer reached the Wimbledon second round when Alexandr Dolgopolov quit when trailing 6-3, 3-0 after just 43 minutes on Centre Court complaining of an ankle injury.

Earlier, title rival Novak Djokovic booked his second round spot in just 40 minutes when Martin Klizan, suffering from a calf injury, retired at 6-3, 2-0 down.

It meant that the Centre Court crowd had seen just 83 minutes of action involving the two men who have won 10 Wimbledon titles between them.

"I feel for the crowd," said Federer. "They're there to watch good tennis, proper tennis. At least they see the two of us who gave it all they had. They saw other players that tried at least."

Five men have retired from the first round -- on Monday, Victor Troicki quit after just 20 minutes.

First round losers all receive £35,000 ($45,220).

There is a rule on the main ATP Tour, but not at the Slams, that an injured player can give up his place to a 'lucky loser' from qualifying while keeping the prize money.

The thinking behind the move is to preserve the integrity of a tournament and prevent fans from feeling short-changed.

But Federer does not want to see the Slams opt for the best-of-three sets format rather than the traditional best-of-five.

"I hope it doesn't happen. But I believe that more players clearly would finish their matches," said Federer who is bidding for a record eighth Wimbledon title.

"A player should not go on court if he knows he should not finish. The question is, did they truly believe they were going to finish.

"If they did, I think it's okay that they walk on court. Otherwise, I feel they should give up the spot.

"The ATP has adjusted its rule. Maybe the slams should have a look at what they could do for the players to make it just a little bit easier."

Federer believes that players who insist on competing in the first round despite obvious physical ailments should not necessarily be damned.

"For some, they just want to be out there because they feel like miracles happen: maybe the other guy retires, or maybe the other guy is carrying an injury.

"If I win, I have a day off, maybe I will feel better on Thursday. All these things play into the equation as well. Don't forget those things as well. Could be rain, come back the next day. You never know what the player's motives are."

Djokovic said he backed the ATP rule being used at the Slams but also refused to criticise opponents who fail to finish.

"If you walk out on the Centre Court, there is a responsibility. I'm sure they tried their best, but it is what it is," said the Serb.

Federer now has 85 match wins at the All England Club, passing the mark he shared with Jimmy Connors.

He also hit his 10,000th career ace in the eighth game of the first set on Tuesday as he set up a clash against Dusan Lajovic of Serbia for a place in the last 32.

The 35-year-old Federer, seeking a 19th Grand Slam title and bidding to become the oldest champion at the All England Club, played down the tag of favourite for a trophy he last lifted in 2012.

"Just because I haven't played the clay court season doesn't make me the favourite," he said.

"You would think that somebody who has played well, like Rafa (Nadal) on the clay courts, he would be feeling really good about his chances here and I'm sure he does feel that way.

"The same for (defending champion) Andy Murray, same for Djokovic.

"Everybody's got a chance to win Wimbledon and for me it's no different. I already achieved my dream to be back here healthy. Now we'll see how far I can go."