Andy Murray was knocked out of the Australian Open in five sets today, losing 2-6, 6-1, 1-6, 6-3, 6-4 to Spain's Fernando Verdasco.

The British No1, looking to reach the last eight here for the first time, came into the fourth-round match having not dropped a set but found the 14th seed in formidable form.

Murray had struggled with headaches and a sore throat prior to Saturday's clash against Jurgen Melzer and looked a shadow of the player who had come to the Open unbeaten in 2009 and a favourite for the crown.

But he refused to blame his recent illness for undermining his bid to give Britain its first Grand Slam men's champion for 73 years.

The 21-year-old said: "If I say I am sick then people will say I am making excuses for losing. If you go on the court then you have to give whatever you have.

"It's not the reason I lost this match because he was just too good for me. His first serve was awesome in the last two sets and I have to deal with this defeat.

"It was like my first round loss to Jo-Wilfried Tsonga here last year and I came back stronger after that defeat and I will go away and work harder and come back stronger again.

"That was a tough loss to take last year but I want to make it clear I didn't lose because of a physical reason even though I was sick for a couple of days. I will learn from this defeat and will come back a better player.

"I had my chances but I started two of the sets badly and he just served huge out there."

Murray had beaten Verdasco on their previous five meetings and took the opening set 6-2 in just 35 minutes. Despite that, he failed to produce the power tennis that had allowed him to beat Rafael Nadal, Roger Federer and Andy Roddick this year as he recorded 11 wins in a row in all events. It followed a gruelling three-week “boot camp” in Miami which had made him stronger and fitter and a successful defence of his Doha title earlier this month suggested Murray really was ready to join the elite of the sport.

Although he did get into the US Open Final last September, this loss will raise questions about his ability to win a Slam and whether he has the mental strength to last two weeks at the biggest tournaments.

Murray added: “I will speak to my coach, the guys that I work with, and see if there's things that I could have done better, things that I can improve. For me, it's not a disaster. I'm still playing well and I lost to a good player in a very close match. I will have more chances to win Grand Slams. I had my chances but he served incredibly in the fourth and fifth sets and deserves the credit for the win.”

While Murray is out, world No1 Nadal marched into the quarter‑finals with a 6-3, 6-2, 6 -4 victory over 13th seed Fernando Gonzalez.

Although Nadal was pleased with his display, he thinks he can get even better. He said: “I think I played well — a very solid match from the baseline, playing very good forehands, backhands.

“Maybe the only thing today I can improve a little bit more for sure is the serve. My serve wasn't very bad, but it was better in the last match.”