Djokovic, Sabalenka in action as Shelton faces Carreno Busta battle

The U.S. Open second round kicks off on Wednesday, with Novak Djokovic pursuing his quest for a record 25th Grand Slam title, while women's top seed Aryna Sabalenka continues her title defence and home favourite Ben Shelton faces veteran Pablo Carreno Busta.

TOP MEN'S MATCH: NOVAK DJOKOVIC V ZACHARY SVAJDA

A 25th major title has eluded Novak Djokovic at the last seven slams. If the 38-year-old fails to win the U.S. Open, he will complete two calendar years without a Grand Slam title for the first time since 2010.

On paper, the Serbian got off to a decent start, beating Learner Tien in straight sets. But the 19-year-old forced a tiebreaker in the second set as Djokovic struggled with a right foot blister.

"Yeah, it's slightly a concern. I don't know. I don't have any injury or anything. I just struggled a lot to stay in long exchanges and recover after points," Djokovic said after the win.

"There was quite a bit of tension on the court, playing a young American... I had to deliver my A-game, which I did I think in the first set. Particularly in the second, it was surviving on the court."

Djokovic is set to face another young American in the second round, and it remains to be seen if the 22-year-old Zachary Svajda can cause problems for the veteran.

TOP WOMEN'S MATCH: ARYNA SABALENKA V POLINA KUDERMETOVA

Three-time Grand Slam winner Aryna Sabalenka said it took her some time to get going when she began her title defence against Rebeka Masarova with a 7-5 6-1 win on Sunday.

"I feel like I didn't start my best in the first game, but then I found my rhythm," the 27-year-old said.

Sabalenka faced her second-round opponent Polina Kudermetova at the Brisbane International in January, where the world number one lost the first set before