Novak Djokovic began his campaign to win a record 25th Grand Slam title with a straight-sets win over Radu Albot at the US Open on Monday.

The four-time champion, playing for the first time since claiming Olympic gold two weeks ago, defeated the Moldovan qualifier 6-2, 6-2, 6-4.

Djokovic arrived on Arthur Ashe Stadium for his 40th career night match at the tournament with two gold bags slung over his shoulder in a nod to his recent Olympic success in Paris.

The 37-year-old, who has lost his Australian and French Open titles this year, was barely troubled by 138th-ranked Albot who has never defeated a top 10 player.

His straightforward victory was also a record 78th on the sport's biggest court.

"The night sessions here are the best in the world and since the roof was added, it's got even louder," said Djokovic.

"There's an incredible energy and with the new rule this year that the crowd can move around, there are lot of things happening."

Second seed Djokovic broke for a 3-2 lead in the opener and was a break to the good in the third game of the second.

Albot rallied to level but the Serb superstar raced away with the next four games to open a two sets lead.

Djokovic broke again for a 4-3 lead in the third and wrapped up victory shortly before midnight.