World number one Novak Djokovic began his US Open campaign with victory over Poland’s Jerzy Janowicz – despite the Serb requiring treatment to his arm.
Djokovic, who has struggled with a wrist injury, won 6-3 5-7 6-2 6-1 after calling the trainer in the first set.
Spanish fourth seed Rafael Nadal beat Uzbekistan’s Denis Istomin 6-1 6-4 6-2.
Germany’s Angelique Kerber, seeded second in the women’s draw, led Polona Hercog 6-0 1-0 when the Slovenian succumbed to leg cramps.
Djokovic had spoken ahead of his opening match about the left wrist injury that has hampered him since the Olympics, but it was the right arm that appeared to be troubling the Serb against Janowicz.
He called a medical timeout after the fifth game to allow the trainer to work on his elbow and upper arm, but promptly broke the Janowicz serve on his way to the first set.
The defending champion began the second set serving at below 90mph but Janowicz was too inconsistent to take advantage, and Djokovic eventually ran out a comfortable winner – at least in terms of the scoreline.
He goes on to face Jiri Vesely in round two – the Czech who beat him in Monte Carlo earlier this year.
