Last updated on .From the section Tennis

Rafael Nadal is the best player in the world heading into the US Open final, says world number one Novak Djokovic.

The top two seeds will meet for the 37th time, and sixth in a Grand Slam final, at Flushing Meadows on Monday.

And after one win apiece in their previous US Open finals, Nadal's form this year has made him many people's favourite to win a 13th major title.

Head-to-head Djokovic Nadal 26 Age 27 44/8 2013 won/lost 53/3 3 2013 titles 9 513/131 Career won/lost 636/125 37 Career titles 59 6 Grand Slam titles 12 $51,645,610 Prize money $56,910,697

"With no doubt he's the best player in the moment this year," said Djokovic, a six-time Grand Slam champion.

"It's always the biggest challenge that you can have in our sport now. I mean, he's the ultimate competitor out there.

"He's fighting for every ball and he's playing probably the best tennis that he has ever played on hard courts."

Nadal, 27, has won all 21 matches on hard courts this year since returning from a seven-month lay-off because of a knee injury, and dropped serve just once while powering through the draw in New York.

He also leads the head-to-head 21-15 and has won five of his last six matches against Djokovic, including a dramatic semi-final victory at the French Open, after the Serb had won seven times in a row in 2011 and 2012.

"I prefer to play against another opponent," joked Nadal. "Talking about a final, I want to play against a player that I have more chances to win.

"Novak is a great opponent. There are other ones, but it's true we have already played a lot of important matches for our career, so that makes that confrontation special.

"And when you have the chance to win against the most difficult players, it's true that the victory is more special.

In-form Nadal Nadal has won all 21 hard-court matches he has played in 2013

He had won 88 consecutive service games until Gasquet broke him

Nadal has lost just 52 games in total at Flushing Meadows this year

He has hit 113 forehand and 28 backhand winners, plus 17 aces

Nadal has spent 12hrs 59mins on court, compared to 12hrs 55mins for Djokovic

"But not in a final of the US Open. In the final of the US Open, what's really is important is to win the tournament, not the opponent."

The final has been scheduled for a Monday this year, having been postponed until Monday for the last five years because of rain.

It has given the men's finalists the guarantee of a day off between the semi-finals and final, but leaves the controversial three-day opening round in place.

"I'm not in support of a Monday final, but this is what it is," said Djokovic, who is appearing in his fifth final in New York, and fourth in a row.

"I mean, it's just an ongoing subject with the US Open and with people who are in organisation here. I don't see why the US Open should get an exception in that."

Nadal was in agreement, saying: "I like to finish the tournament on Sunday, not on Monday."

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Djokovic said he was "physically fine" after his five-set semi-final win over Stanislas Wawrinka, and knows what to expect on Monday.

"The way he's been playing he's very confident, but I know how to play him," said Djokovic.

"Hard court is the surface that is my most successful. I have played him already here twice in the finals. I know what I need to do.

"Now it's of course easier to sit here and say, 'I know what I need to do,' but I've got to do it on the court. I'll be ready to give everything I have for the trophy."