A win at Wimbledon this year won’t be in the cards for seven-time singles champion Serena Williams after she injured herself during the first set of her first round match against Aliaksandra Sasnovich. After slipping on the grass while planting one of her legs, Williams injured her knee. She was treated by a trainer and tried to continue the match but eventually fell to the ground in tears when she landed on the knee again. She then had to retire from the match. It’s only the second time an injury has forced Williams to retire from a Grand Slam—the other time was Wimbledon in 1998. The rainy weather has led to other players slipping. France’s Adrian Mannarino slipped on the grass during his match against Roger Federer, causing an injury that forced him to retire. Novak Djokovic slipped several times during his match on Monday but was able to come out injury-free.

If Williams’ injury keeps her out of the U.S. Open, she might not be seen on a court again until the start of next season.