Novak Djokovic continued his bid for a record 25th Grand Slam title in style as he stormed past qualifier Jan-Lennard Struff to reach the US Open quarter-finals.
Despite twice receiving medical attention, the Serb rarely looked troubled as he raced to a dominant 6-3 6-3 6-2 victory in under two hours.
While the win was further evidence of Djokovic's pedigree, questions still remain over the 38-year-old's physical condition.
Djokovic is playing his first tournament since losing in the Wimbledon semi-finals in July, having skipped ATP Masters events in Toronto and Cincinnati.
He looked fatigued in his opening two matches in New York, while he struggled with a lower back injury in his third-round win over Britain's Cameron Norrie.