A downcast Andy Roddick blamed a shoulder injury for robbing him of the "full deal" during his five-set quarter-final loss to Croatia's Marin Cilic on Tuesday.
The seventh-seeded American struggled with the injury from the first set and took medical treatment in the second, but after battling back to square the match, he went down 7-6 6-3 3-6 2-6 6-3 at Rod Laver Arena.
"Yeah, the arm was -- I don't know what happened. I felt it a little bit the other night, the cold weather, trying to hit through those for a little while. I didn't hit yesterday," the 27-year-old told reporters.
"Felt pretty good today in warm-up, the first couple games, then I think I aggravated something.
"The trainer said it was stemming from the neck down. By the end of the first set, I was pretty numb in the bottom two fingers.
"I could still hit it pretty hard, I was just having trouble controlling it. I didn't really have full deal."
At 0-0 in the fifth set, Roddick manufactured three break points on Cilic's serve but was unable to convert them.
It was the last time the American had a look at 14th-seeded Cilic's serve, as the Croatian broke him to take a 3-1 lead and calmly rode out for victory.
"To be able to push it and have a shot, I thought it was a pretty good effort," said Roddick, whose 2003 U.S. Open success was the last grand slam title clinched by an American man.
Roddick leaves with a sixth trip to the quarters out of nine appearances at Melbourne Park, where has never progressed beyond the semi-finals.
Cilic, who reached his first grand slam semi-final with his third five-set victory at the tournament, would be hoping potential opponents Rafa Nadal and Andy Murray "go long" during their quarter-final on Tuesday night, Roddick said.
"He's definitely composed ... He just goes about his business, does it the right way, and seems like a very hard worker.
"He doesn't give you any encouragement, like the feeling you're on top of him, even though I probably was for a little while.
"That being said, five setters are five setters. I'm sure he'll be a little tired."