By Michael Bennett

Roger Federer’s play last night was as sluggish as the air in Ashe Stadium, and it will be 29-year-old Aussie John Millman facing Novak Djokovic in the quarterfinals after a 3-6, 7-5, 7-6 (7), 7-6 (3) victory.

The match ended shortly before 1 a.m. today.

“He’s been a hero of mine,” Millman said of Federer in an on-court interview. “Today he was definitely not at his best, but I’ll take it.”

Federer’s serve, normally a reliable weapon, deserted him. He had 10 double faults, including two in the fourth-set tiebreaker. He got only 49 percent of his first serves in, including an abysmal 31 percent in the second set that turned the match around. He won only 47 percent of his second-serve points.

Federer served for the second set, but was broken. He was ahead in the third-set tiebreaker, and lost it. He had 77 unforced errors, the last a forehand that went long on match point.

Millman countered with 47 winners and 28 unforced errors, and did not falter after going down a break at 2-4 in the fourth set. He broke Federer in the next game.

“One thing I can control is the fight in me,” Millman said.

As the match wore on, the 37-year-old Federer seemed to be weighed down by the heat and humidity. He did not move with his customary grace, and his shots did not land with their customary precision.