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 made it five over the course of two days at the Championships.