(Reuters) - American Mardy Fish survived a huge scare as he recovered from two sets down to beat Russia's Nikolay Davydenko and reach the third round of the U.S. Open on Thursday.

The 23rd seed began slowly but found his form just in time to clinch a 4-6 6-7 6-2 6-1 6-2 victory and become the 10th man in the tournament to win from two sets down.

At 31, former world number three Davydenko has slipped to 47th in the rankings but a shock looked possible when he won the second-set tiebreak.

But Fish found his form just in time and punched the air when a Davydenko forehand landed wide to set up a clash with number eight seed Gilles Simon of France or Jimmy Wang of Taipei.