Nadal looked in trouble at a break down in the third set

The Spaniard, who had heavy strapping on both knees, needed treatment for tendonitis during the match.

Jones, the world number 123, was a break up in the third set before Nadal roared back to win 7-5 3-6 6-4 6-1.

World number one Roger Federer beat Chile's Paul Capdeville 6-1 6-4 6-4 in Wednesday's late match.

"I'm very happy the way I played. I think I hit the ball well," said Federer, who made just 11 unforced errors in the match.

World number two Nadal said: "Maybe in another tournament I never go to the court today, but it is US Open and it is very important to me.

"I have more than one day now and I hope it will improve. It's tough when you can't play at 100% in a very important tournament like this.

"But for me, the tournament is not finished. I'm still there."

606: DEBATE It's actually quite ominous for Nadal's rivals that he played so bad and still won final_word

Nadal, who will meet Janko Tipsarevic in the second round, added: "My knee was fine three days ago but I was practising and in the last minute I felt something.

"The next day I didn't practise. Yesterday I practised 35 minutes. I hope the knee improves. I can't move too much and I spoke with my coach before going on court, he said 'just try to move as little as possible and try to win'.

"I had an MRI (scan) yesterday and it's not a big problem but sure, it's difficult to play like this."

There was a shock on Court 13, where seventh seed and Australian Open finalist Fernando Gonzalez of Chile made an early exit to Russia's Teimuraz Gabashvili.

In a match that lasted just under three hours, Gabashvili withstood a Gonzalez fightback to come through 6-4 6-1 3-6 5-7 6-4.

"You have many good opponents and they are always trying to win and the higher ranking you are, they have more motivation to try and beat you," said Gonzalez.

"I'm practising really hard. When you're not winning matches you lose confidence and that's a very important thing in tennis."

I'm kind of not expecting anything from this tournament Marat Safin

Marat Safin avoided an upset in round one with a 7-5 7-6 (7-5) 7-6 (9-7) win over danger-man Frank Dancevic.

Dancevic reached the Indianapolis final earlier this summer, beating Andy Roddick on the way, but Safin made him pay for not taking his chances.

The Canadian served for the second and third sets but 2000 champion Safin, who showed only glimpses of his brilliant best, fought back each time.

Safin will face Switzerland's Stanislas Wawrinka in the second round.

"I'm kind of not expecting anything from this tournament and nothing from this year, but at least I started to play better," said the Russian.

"For me to make the quarter-finals lately, it's a huge, huge deal."

Mikhail Youzhny, last year's semi-finalist, got his 2007 campaign off to an impressive start with a 6-0 6-1 6-2 win over US Open debutant Nicolas Devilder of France.