"I thought that the match was tough," Federer told reporters. "I wish I could have led two sets to love and maybe the match would be different. Maybe I'd find a way. Because I did have my chances all the way until the end but it was just tough. John I think played a great match in difficult conditions."
No. 7 Marin Cilic is still alive after eliminating David Goffin in three sets on Sunday. No. 6 Novak Djokovic also advanced, beating Joao Sousa in three sets. No. 21 Kei Nishikori also eliminated Philipp Kohlschreiber in three sets on the men's side.
No. 14 Madison Keys won her women's singles match against No. 29 Dominika Cibulkova in straight sets. No. 30 Carla Suarez Navarro eliminated No. 22 Maria Sharapova in straight sets. No. 20 Naomi Osaka and unseeded Marketa Vondrousova also advanced.
In the women's draw Tuesday, No. 17 Serena Williams faces Karolina Pliskova at 7 p.m. Fellow American and No. 3 seed Sloane Stephens has a quarterfinal matchup against No. 19 Anastasija Sevastova at noon.
On the men's side, No. 1 Rafael Nadal faces No. 9 Dominic Thiem at 8:15 p.m. in a men's quarterfinal. The other men's quarterfinal pits No. 3 Juan Martin del Porto against No. 11 John Isner at 1:30 p.m. in Arthur Ashe Stadium.