NEW YORK: Andy Murray has to wait an extra night to see if he can complete a stunning upset of world number one Rafael Nadal and reach the US Open finals against four-time defending champion Roger Federer.

Murray surged to a 6-2, 7-6 (7/5), 2-3 lead over the reigning French Open and Wimbledon champion in a Saturday semifinal, with Nadal up a break in the crucial third set when rain from Tropical Storm Hanna sent them off the court. Murray could become only the third British man to reach a Slam final, after Greg Rusedski in the 1997 US Open and John Lloyd at the 1977 Australian Open, and the first to win a Slam crown if he could topple Federer in the final.

Nadal is trying to become only the second Spaniard in the 40-year Open era to win the US title, the first being Manuel Orantes in 1975 when the event was played on clay. Nadal, who has won 19 Grand Slam matches in a row, is trying to join Pete Sampras, Roger Federer and Rod Laver as the only men to win three Slams in a row in the 40-year Open era.

Murray won the first set in 34 minutes, firing 13 winners to only four by Nadal, and forced Nadal to save three break points in the third game of the second set and two more in the fifth game before fighting to the tie-breaker.

A service winner gave Murray a 6-5 edge in the tie-break and the 21-year-old Scotsman claimed the set when Nadal sent a cross-court backhand wide, pumping his fists and yelling, “Come on,” as he seized command of the match. The joy was short lived. Nadal, in his first US Open semifinal, broke Murray to open the third set and was about to serve when the rains came.

Tournament officials moved the match to Louis Armstrong Stadium from Arthur Ashe Stadium in hopes of out racing the rain drops, but did not start it until 40 minutes after noon.

Swiss second seed Federer’s 6-3, 5-7, 7-5, 6-2 triumph over Serbian third seed Novak Djokovic began about 90 minutes before Murray and Nadal began and the time difference made the difference between finishing and not.

Spectators were told the Murray-Nadal match would resume at Ashe stadium on Sunday at 4 pm but organisers would only say it would be resumed Sunday. Tournament officials also would not confirm that the men’s final would be played Monday, the first time since 1987 that the US Open would need an extra day to finish play.

Whenever he takes the court, Federer will face a foe who has an edge in their head-to-head rivalry. Murray leads Federer 2-1 after a victory at Dubai in March while Nadal owns a 12-6 edge on Federer, including a blowout win in the French Open final and an epic 6-4, 6-4, 6-7 (5/7), 6-7 (8/10), 9-7 triumph in the Wimbledon final. Federer admitted that he would rather resume his rivalry with Nadal, 22, rather than see new comer Murray across the net from him for the trophy.