Roger Federer was mortified learning of Serena Williams' stunning exit from Wimbledon with a knee injury.
It was disaster day at Wimbledon as Williams' quest to capture a record-tying 24th Grand Slam championship came crashing down as she suffered a fall forcing her to retire from her opener against Aliaksandra Sasnovich.
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Informed of Williams' injury-induced exit during his press conference, Federer initially expressed disbelief saying "come on."
Learning his friend and fellow 39-year-old Slam champion was indeed out of the tournament, Federer summed up the sentiments of the tennis world saying: "Oh, my God, I can't believe it."
The sixth-seeded Swiss had forced a fifth set in his Wimbledon opener on Centre Court when Adrian Mannarino was forced to retire from the match after injuring his right knee in a fall to the lawn late in the fourth set.
Williams and Sasnovich followed Federer onto Centre Court where the four-time Olympic gold-medal champion's slip ultimately led her to retire in tears deadlocked at 3-all.
It was just the second time in her career Williams retired from a Grand Slam match and the first time since 1998.
Federer, who has come back from two right knee surgeries, said the grass is typically most slick and slippery during the first two rounds before repeated play creates brown patches behind the baseline.
"This is obviously terrible. Yeah, I don't think it plays very different," Federer said. "Again, I'm also moving carefully. This is what I told the team, as well. They thought I moved very well. Under the circumstances, those first two matches are always extremely difficult.
"But it's always been like this. I feel for a lot of players it's super key to get through those first two rounds because the grass is more slippery, it is more soft. As the tournament progresses, usually it gets harder and easier to move on. This is obviously terrible that it's back-to-back matches and it hits Serena as well."