Roger Federer, seeded second, has won in Cincinnati a record seven times but hasn't played at the venue since winning in 2015. In 2016, he had a knee injury, and in 2017 he had back problems.

"Cincinnati has always been a good tournament for me," said Federer, the reigning Australian Open champion. "I was sad not to play here last year, and two years ago there wasn't a chance. I'm glad to be back."

Even with the top-ranked Nadal missing, Federer liked the strength of this field, especially with Murray and Wimbledon champion Novak Djokovic also successfully recovering from injuries.

"That's why you have such a good, exciting draw," Federer said before Murray's match was over. "It's a pity Rafa isn't playing. He would have added massively to that part of the draw."