AMSTERDAM: Former World No. 4 Kiki Bertens announced Thursday that she will retire at the end of the 2021 season. The 10-time winner from the Netherlands underwent Achilles surgery last October. “I want to share with all of you that I have decided this year will be the last season of my tennis career,” Bertens said on Instagram. “I have always demanded the maximum of myself, but the tank is quite empty. The balance of the hard work I put in day in and day out and the satisfaction I get out of it at the end of the day is no longer there.” Bertens, 29, said she plans to play Eastbourne, Wimbledon and the Olympics in Tokyo before deciding if she will play in any other events later in the year. “I’m really happy that I can end it this way,” said Bertens, who is currently ranked No. 20. “That I can hopefully end it in the right way with some nice results, but I’m proud of the career that I had.” Bertens’ best showing in a Grand Slam event came in 2016 when he reached the semifinals of the French Open before losing to Serena Williams.