By Simon Cambers

NEW YORK (Reuters) - Scottish teenager Andy Murray has an uphill battle if he is to reach the last eight of a grand-slam event for the first time when he resumes his U.S. Open match with Russian Nikolay Davydenko on Wednesday.

Murray was trailing the seventh seed two sets to one when rain forced an end to the match.

In the men's event, former champions Andy Roddick and Lleyton Hewitt also square off for a place in the semi-finals.

Their match is a repeat of the 2001 quarter-final which Hewitt won in five sets. The Australian has won six of their eight career matches, although Roddick won the most recent, in Cincinnati last year.

Second seed Rafael Nadal, in the quarter-finals for the first time, takes on Russian Mikhail Youzhny in the day's other quarter-final.

In the other fourth-round action, top seed Roger Federer will continue his bid to win a third consecutive U.S. Open title when he takes on little-known Frenchman Marc Giquel.

Giquel upset 21st seed Gaston Gaudio in the third round but world number one Federer has not dropped a set in his first three matches and is well on course to follow John McEnroe and Ivan Lendl in winning three straight years at Flushing Meadows.

Fifth seed James Blake bids to reach the quarter-finals for the second year in succession when he faces Tomas Berdych of the Czech Republic.

Finally, former champion Marat Safin, resumes 2-1 up with a break against German 14th seed Tommy Haas.