Alexandr Dolgopolov became the latest player to withdraw from Wimbledon on Saturday, citing a wrist injury.
The Ukrainian joins Switzerland's Timea Bacsinszky, who also pulled out on Saturday, Chung Hyeon of South Korea and Spain's Roberto Bautista Agut, who both decided they would not play on Friday.
World No. 64 Dolgopolov was at the centre of controversy at Wimbledon last year when he lasted only nine games against Roger Federer in the first round before retiring hurt.
On the same day, also on centre court, Martin Klizan pulled out after just eight games against Novak Djokovic.
The spate of retirements forced a rule change which means this year players who withdraw in the first round with a pre-existing injury risk losing all of their £39,000 ($51,515) worth of prize money.
However, a player who withdraws before their match can collect 50 percent of their first-round losers' fee.
Dolgopolov was replaced by "lucky loser" Simone Bolelli, while Bacsinszky -- who withdrew from the women's singles with a right lower-leg injury -- was replaced by Mariana Duque-Marino, of Colombia.