NEW YORK    -   Novak Djokovic is through to the third round at the U.S. Open and will use some of the time until then getting more treatment on his left shoulder. Djokovic fought through trouble with the shoulder to beat Juan Ignacio Londero 6-4, 7-6 (3), 6-1.

The defending champion was treated by the trainer multiple times in the match and appeared in trouble when he fell behind 3-0 in the second set. But he battled back to take it in a tiebreaker and had an easy time in the third set. The No. 1 seed wouldn’t reveal much about the nature of the injury in his post-match interview. “I’ve been experiencing some days of higher intensity of pain, some days less. It has been really fluctuating a lot, going up and down,” said Djokovic. “What happened today on the court, actually how I felt, was quite rough and unpredictable.”

So bothered was Djokovic by his backhand that in the third game of the second set, at 30-30 and with Londero well out of position, he failed to get even a soft backhand to the open court over the net. But he roared back to take the next five games, a stretch during which he managed to fire off a number of backhand winners, en route to strolling through the tiebreak before getting more treatment on his shoulder.

“It was not easy to play with this kind of sensation, to be honest. I did not experience that too many times in my career,” said Djokovic. “The way it has started for me, especially midway through the first set, I didn’t know if I would be able to finish the match.”

Serena Williams has avoided what would have been her earliest loss in 19 appearances at the U.S. Open. Williams came back from a set down in the second round at Flushing Meadows to beat 17-year-old American Caty McNally 5-7, 6-3, 6-1. The only time Williams ever has been beaten as early as even the third round in New York was in her tournament debut all way back in 1998 — when she was just 16 herself. The following year, Williams won the first of her six U.S. Open championships. McNally hadn’t even been born yet.

“She really came out and played really well, she showed no fear,” said Williams. “She had absolutely nothing to lose and she played like it. “I survived tonight,” said Williams. “I am not too pleased with the way I played at all,” said Williams, whose 28 unforced errors were two fewer than McNally. “But it’s OK, I’m alive, I’m still here and happy to be on this court. I’ll do better. I promise.”

Second-seeded Ash Barty barely avoided getting pushed to a third set and got past Lauren Davis of the United States 6-2, 7-6 (2) to reach the third round at Flushing Meadows. Barty won the French Open in June and is trying to get past the fourth round in New York for the first time.

Venus Williams needed a little pick-me-up on a rainy day in New York. It takes more than caffeine to beat Elina Svitolina, though. Williams had a resurgence after some coffee was sent her way after dropping the first set against the No. 5 seed, but Svitolina charged back and eventually beat Williams 6-4, 6-4 in a second-round match. Williams fought off five match points in a 22-point game to hold her serve before Svitolina eventually ended it on her sixth chance, improving to 13-3 in Grand Slam matches this season.

Roger Federer once again came back from a set down to advance at the U.S. Open, beating Damir Dzumhur 3-6, 6-2, 6-3, 6-4. The second-round match was very much like the opener for the third-seeded Federer, who dropped the first set against qualifier Sumit Nagal before cruising the rest of the way.

Federer again stepped up his game against the 99th-ranked Dzumhur, winning 77 percent of his first-serve points and blasting 58 winners, more than double that of his opponent.