Roger Federer and Novak Djokovic encountered different issues on their way to the US Open third round on a rain-hit Wednesday.

Only four men's singles matches were completed – and there was a withdrawal – as the weather caused problems in New York.

Still, Federer and Djokovic managed to get through their second-round matches, but it was not easy.

FEDERER RUSTY AGAIN

Federer made another slow start before getting past Damir Dzumhur 3-6 6-2 6-3 6-4.

The Swiss 20-time grand slam champion lost the opening set, as he did against Sumit Nagal in the first round, on the back of 17 unforced errors.

Federer again managed to recover, the five-time champion at Flushing Meadows progressing after two hours, 22 minutes.

INJURY WORRY FOR DJOKOVIC

Djokovic, meanwhile, claimed a 6-4 7-6 (7-3) 6-1 victory over Juan Ignacio Londero, but had problems of his own.

The Serbian defending champion needed treatment on his left shoulder during his win as he was pushed in the opening two sets.

While forced to come from behind in each of the first two sets, Djokovic dealt with the shoulder issue to move through.

NISHIKORI, DIMITROV INTO THIRD ROUND

Kei Nishikori, the 2014 runner-up, battled through thanks to a 6-2 4-6 6-3 7-5 win over Bradley Klahn.

The Japanese seventh seed was one of five men to advance, with Grigor Dimitrov joining him.

Dimitrov was scheduled to face Borna Coric, but the Croatian 12th seed withdrew due to a lower back strain.

The final man to advance was Dominik Koepfer, who got past Reilly Opelka 6-4 6-4 7-6 (7-2).