Roger Federer and Novak Djokovic said Wimbledon should consider rule changes after both their first-round opponents retired with injuries.
Third seed Federer led 6-3 3-0 when Ukrainian Alexandr Dolgopolov quit with an ankle injury after 43 minutes.
Second seed Djokovic progressed after a calf injury saw Martin Klizan pull out at 6-2 2-0 down on 40 minutes.
“We had a joke in the locker room saying we should maybe play a practice set on Centre Court,” said Djokovic.
Both Klizan and Dolgopolov have struggled with injuries recently and their retirements were among seven in the men’s draw and one in the women’s over the first two days of the Championships.
The men’s tour, the ATP, introduced a rule at the start of 2017 that means a player can retire before a first-round match and retain their prize money.
A lucky loser then gets the place and money earned from qualifying, plus any further prize money accrued from the second round onwards.
The rule is not in place at the four Grand Slam tournaments.
“Maybe it should be addressed,” said Djokovic.
“I think the new rule that the ATP has reinforced allows players who deserve already, who have made it to the Grand Slam main draw, to get what they deserve, but at the other hand allow someone else to play if they can.
“I support that kind of rule.
First-round losers at Wimbledon earn £35,000 this year, potentially encouraging players to take to the court when they know they are not fit enough to compete.
“The question always is, should they have started the match at all?” said Federer.
“That, only the player can answer really, in my opinion. You hope that they would give up their spot for somebody else, even though they deserve to be in there, but fitness not allowing them.
“Maybe the Grand Slams should adopt some of [the ATP rule], then maybe we would eliminate maybe half of the players [who retire],” said Federer.
“Some of them, maybe something really did happen. Now you’re thrown in the same basket, so that’s rough.”