Djokovic is seeded to meet Lleyton Hewitt in the last 16

Haase only won a place in the main draw when Mario Ancic pulled out with an injury but it proved to be a brief stay in the main draw for the 20-year-old.

Lleyton Hewitt and James Blake were other big names to make progress on day two in New York.

And American fifth seed Andy Roddick wrapped up Tuesday's play by beating Justin Gimelstob 7-6 (8-6) 6-3 6-3.

News conference: Lleyton Hewitt

"I could have cut down the errors a little on the baseline, but Justin makes it awkward because he's coming toward you at the net," said Roddick.

Sixth-seeded compatriot Blake saw off a spirited Michael Russell 7-6 (8-6) 6-3 7-6 (7-4), and said: "I feel great about how I played today. I think everyone saw how much he made me work so it's a fun match for me to win."

Hewitt, the 2001 champion, took just over an hour and a half to thrash American Amer Delic 6-2 6-4 6-2.

Now I have more confidence and belief that I can do well in the Grand Slams Novak Djokovic

The Australian did not face a single break point against a game but limited opponent.

"Delic is the kind of guy, you give him the half opportunity he's going to take it, come to the net, put pressure on you," said Hewitt.

"He doesn't have the best passing shots out there so it was a matter of me mixing it up when I had the opportunity, come in on his backhand, make him press."

The former world number one will next face Agustin Calleri of Argentina.

Djokovic opened with a convincing win over Haase that illustrated why he has shot up to three in the world rankings this year.

606: DEBATE Have your say on the day's action in New York

"It's always good to get the first match done in the fastest possible way," said the Serb, who beat Roger Federer and Rafael Nadal on his way to winning in Montreal earlier this month.

"I was playing against a lucky loser but I did not want to underestimate my opponent and I was even a little bit nervous at the start.

"In Montreal I played the best tennis in my life and now I have more confidence and belief that I can do well in the Grand Slams and at the US Open."

Djokovic, expected to be one of Federer's main rivals for the title, will now face Radek Stepanek.

Other seeds to advance on Tuesday were Ivan Ljubicic, Juan Ignacio Chela and Jurgen Melzer.

And former semi-finalist and 24th seed David Nalbandian had to work hard to beat Ivan Navarro 7-5 7-6 (7-4) 7-6 (8-6).