Roger Federer of Switzerland hits a return during the men's singles fourth round match against Adrian Mannarino of France at the Wimbledon Championships 2018 in London, Britain, on July 9, 2018. Roger Federer won 3-0. (Xinhua/Stephen Chung)

Roger Federer of Switzerland hits a return during the men's singles fourth round match against Adrian Mannarino of France at the Wimbledon Championships 2018 in London, Britain, on July 9, 2018. Roger Federer won 3-0. (Xinhua/Stephen Chung)

Adrian Mannarino of France competes during the men's singles fourth round match against Roger Federer of Switzerland at the Wimbledon Championships 2018 in London, Britain, on July 9, 2018. Adrian Mannarino lost 0-3. (Xinhua/Stephen Chung)

Roger Federer of Switzerland hits a return during the men's singles fourth round match against Adrian Mannarino of France at the Wimbledon Championships 2018 in London, Britain, on July 9, 2018. Roger Federer won 3-0. (Xinhua/Stephen Chung)

Roger Federer of Switzerland hits a return during the men's singles fourth round match against Adrian Mannarino of France at the Wimbledon Championships 2018 in London, Britain, on July 9, 2018. Roger Federer won 3-0. (Xinhua/Stephen Chung)

Roger Federer of Switzerland serves during the men's singles fourth round match against Adrian Mannarino of France at the Wimbledon Championships 2018 in London, Britain, on July 9, 2018. Roger Federer won 3-0. (Xinhua/Stephen Chung)

Roger Federer of Switzerland hits a return during the men's singles fourth round match against Adrian Mannarino of France at the Wimbledon Championships 2018 in London, Britain, on July 9, 2018. Roger Federer won 3-0. (Xinhua/Stephen Chung)

Roger Federer of Switzerland hits a return during the men's singles fourth round match against Adrian Mannarino of France at the Wimbledon Championships 2018 in London, Britain, on July 9, 2018. Roger Federer won 3-0. (Xinhua/Stephen Chung)