Djokovic confident as he aims to win his third slam this year

World number one Novak Djokovic lost to rivals Roger Federer and Andy Murray in the finals of US Open warm-up events but the Serb insists those defeats have aided his preparations for the last grand slam of the season.

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"Of course, I did want to win both in Canada (Montreal) and Cincinnati, but it didn't happen," the top-seeded Djokovic told reporters on Saturday at Flushing Meadows.

"But they deserved to win because they were better players on the court. It only changes in terms of me understanding what I did wrong, what has happened in those matches, analysing it...

"Trying to develop the right approach to prepare myself and to get better."

Djokovic is gunning for a third grand slam title this season after winning the Australian Open and Wimbledon crowns and boasts a match record of 56-5.

The 28-year-old Djokovic won three grand slams in 2011 and considers himself an even better player now in some respects.

"I think physically I'm stronger and I'm able to endure longer than I did in 2011," he said.

Despite defeats in the back-to-back finals, Djokovic had a more successful preparation to the US Open than last year, when he won only two matches in Toronto and Cincinnati before losing to Japan's Kei Nishikori in the semi-finals in New York.

The Serb also feels that the foundations of a permanent roof over Arthur Ashe Stadium that will be in place for next year's Open will help his performance by calming the swirling winds that in the past have affected his accuracy.

"I've practised several times in the center court," he said.

"The construction is really impressive and that has protected the court from the wind, so we have less of the swirling conditions on the court, which does help.

"In the past, I've played many matches where it was difficult to control the ball on the court because of the swirling conditions. Now it protects it."

Djokovic, who won the US Open in 2011 but has lost in four other finals at Flushing Meadows, will play his opening match of this year's championships in Monday's opening day session against Brazil's Joao Souza.