Novak Djokovic continues to be troubled by an arm injury but had few problems in getting past Kyle Edmund in the US Open fourth round.
The defending champion, who had spent just over three hours on court at the year's last grand slam, showed some better signs during a 6-2 6-1 6-4 victory on Sunday.
But he again needed treatment on his arm, with his right elbow seemingly the troubled area as he was attended to early in the third set.
Djokovic, the beneficiary of a walkover and retirement in the second and third rounds respectively, showed few signs of rustiness early.
Edmund, the Brit who claimed wins over Richard Gasquet and John Isner on his way to the last 16, instead made far too many errors.
Djokovic cruised through the opening two sets at Arthur Ashe Stadium before treatment slowed him down, Edmund going up a break in the third.
The 12-time grand-slam champion responded immediately, and broke to love in the 10th game to complete his win.
Awaiting Djokovic in the quarter-finals is Jo-Wilfried Tsonga, the Frenchman who has lost 15 of the 21 previous meetings between the pair.
Djokovic has now remarkably reached at least the last eight at the US Open in 10 straight years.
Djokovic  bt Edmund 6-2 6-1 6-4
Djokovic - 24/25
Edmund - 15/36
Djokovic - 3
Edmund - 3
BREAK POINTS WON
Djokovic - 8/15
Edmund - 2/6
FIRST SERVE PERCENTAGE
Djokovic - 62
Edmund - 64
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Djokovic - 75/45
Edmund - 53/31
Djokovic - 101
Edmund - 70