Feliciano Lopez
Lopez played in the men's doubles just a day after pulling out of his single matches against Adrian Mannarino. Getty Images

Wimbledon has been left red-faced once again amid the controversy over prize money after one of the eight players who retired injury during their first round singles match returned in the doubles competition. Spaniard Feliciano Lopez took his total earnings from SW19 above £40,000 after participating alongside compatriot Marc Lopez on Wednesday (6 July), just 24 hours after a supposed knee injury forced him to withdraw from a clash with Adrian Mannarino.

Lopez, 35, was trailing by two sets to one and a break when he retired hurt against Frenchman Mannarino on Tuesday – joining the likes of Martin Klizan and Alexandr Dolgopolov in curtailing their opening round matches. Novak Djokovic and Roger Federer, both of whom were victims of the aforementioned withdrawals, called for a rethink into the ruling that sees the four Grand Slam tournaments pay an appearance fee to players even if they lose in the first round.

But 24 hours after injury ended his singles campaign, Lopez was back in the men's doubles competition – picking up another £5,375 as he and Marc Lopez lost to Australian pair Matt Reid and John-Patrick Smith. The incident will spark further scrutiny over the decision to pay all players who participate in the first round of a major and intensify calls to implement an ATP ruling that sees all qualifiers compensated even if they pull out before their opening match.

A total of eight players pulled out of their round one matches across the men's and women's singles draws. Janko Tipsarevic retired after just 15 minutes into his match with American Jared Donaldson while Nick Kyrgios lasted two completed sets before pulling out of his clash with Pierre-Hugues Herbert.

Denis Istomin followed after falling two-set-to-one and a break down in his match with Donald Young and Viktor Troicki lasted just seven games before Florian Mayer benefitted from the seventh injury in the men's draw. The Serbian's fitness has prevented him from participating in the doubles alongside fellow-countryman Nenad Zimonjic. The only retirement in the women's draw came courtesy of Anastasia Potapova, who was a set down 2-2 with German Tatjana Maria before calling time on the match.

Federer has led calls for a change to the rules that sees first round opponents only paid if they begin their scheduled match. "When I went out, I felt it was a let-down for the crowd," he said of the centre court fans some of whom had queued overnight to watch the 18-time grand slam winner.

"They could not believe that it happened again, exactly the same situation. He called the trainer after the set, pulled out at 3-0, the same thing. I feel for the crowd, they are there to watch good tennis, proper tennis. At least they saw the two of us who gave it all they had. If you feel like it is getting worse and you can hurt yourself further, it is better to stop. The question always is: should they have started the match at all? Only the player can answer really. You hope they would give up their spot for somebody else if fitness is not allowing them."

Each of the Grand Slams are understood to be considering a change to the rules and the implementation of the ATP regulation which came in at the start of 2017.