New York:Andy Murray made a shocking fourth-round exit from the US Open on Tuesday, never looking on form as Croatian 16th seed Marin Cilic reached his first Grand Slam quarter-final with a 7-5, 6-2, 6-2 victory.
The 22-year-old British second seed, last year's US Open runner-up, failed in his bid to become the first British men's Grand Slam champion since Fred Perry in 1936.
"I just struggled," Murray said. "I played poorly. I'm very disappointed. I didn't feel like I played well. I had my chance in the first set and struggled after that."
Defeat on the Flushing Meadows hardcourts was especially stinging for the 22-year-old Scotsman, who loves the surface as well as the atmosphere of a New York fortnight in the year's last Grand Slam event.
"I returned poorly. He served well. That felt like the difference," Murray said. "The momentum was with him and I didn't manage to get it back.
"I'm disappointed. I don't know how long or how quickly it will take me to get over it."
In taking his first victory over a top-three opponent in seven attempts, Cilic fired 10 aces and 35 winners while Murray went 0-for-7 on break-point chances and made 41 unforced errors.
"I played very well and he was missing a lot," Cilic said. "I don't think he was playing his best."
Cilic will play for a semi-final berth against Argentine sixth seed Juan Martin Del Potro, who fired 22 aces and 44 winners to defeat Spanish 24th seed Juan Carlos Ferrero 6-3, 6-3, 6-3.
Del Potro beat Cilic in the fourth round of his year's Australian Open in their only meeting. At 20, they are the youngest players still in the draw.
"I'm happy to be in the quarter-finals. It's a return for me," Del Potro said. "It's like magic."
Chilean 11th seed Fernando Gonzalez booked a date in the last eight by beating French seventh seed Jo-Wilfried Tsonga 3-6, 6-3, 7-6 (7/3), 6-4.
Gonzalez, trying to become the first South American to win the US Open men's singles crown in 32 years, will play the winner of a later match between third seed Rafael Nadal of Spain and French 13th seed Gael Monfils.
"I'm really confident," Gonzalez said. "I have to be worried about myself only and try to play my best tennis."
Six-time Slam winner Nadal, the reigning Australian Open champion who is trying to complete a career Grand Slam, is 6-3 life-time against Gonzalez and 0-2 against Monfils.
Cilic was relieved to finally break into the last eight at a slam after four prior runs were halted in the fourth round.
"That feels really amazing," Cilic said. "It feels great to win that extra set."
Murray had beaten Cilic in their three prior meetings, most recently in the fourth round of this year's French Open, but looked off-form from the start.
Murray had the first break-point chances of the match in the sixth game of the opening set, but a service winner by the Croatian and a wide crosscourt forehand by Murray enabled Cilic to hold for 3-3.
After rescuing a break point in the ninth game, Murray was thwarted on two break points in the 10th game, Cilic saving the first with an ace before Murray netted a backhand.
"That was the turning point," Cilic said. "It was a relief for me to get into the match and not be so into myself."
Cilic broke Murray in the next game, held to win the first set, then opened the second with two breaks for a 3-0 lead. He denied Murray on three more break points in the last game of the second set, then held on back-to-back aces, the last baffling the Briton who swung and missed.
Murray surrendered a break to open the third set and offered up another in the penultimate game before Cilic ended the rout after two hours eight minutes.
Gonzalez took the only break of the final set in the last game, Tsonga sending a forehand volley wide and a backhand volley long to fall in two hours 41 minutes. The Frenchman was denied on 13-of-14 break-point chances.
Gonzalez, the 2007 Australian Open runner-up in his best Slam showing, has not reached the US Open final eight since his first Slam quarter-final appearance in 2002.