Andy Murray believes he can become world No1 within six months if he can win the Australian Open and maintain the form that has made him the hottest player in tennis.

Murray benefited from a farcical first-round victory over Romanian veteran Andrei Pavel on centre court today when the 34-year-old quit after 45 minutes complaining of back pain - and promptly retired from the sport.

The world No4 was 6-2, 3-1 up when the match ended, allowing him to get out of the heat which reached an amazing 122°F at the tennis complex. The conditions were so bad that women players were allowed to used ice vests during change-over and take a 10-minute break between the second and third sets.

Murray is in the spotlight having arrived at the Open on a run of eight wins and with a successful defence of his Doha title to follow his appearance in the US Open Final last September.

Now, with three tournament wins in a row over Roger Federer and victories against Rafael Nadal and Novak Djokovic, all eyes are on the player who is hoping to give Britain its first men's grand slam champion for 73 years.

Murray said: "I would love to be No1 and I am sure all players would at some point in their career.

"I want to try and win a slam first and that's the next step for me. But if I play well in the first six months of this year, when I don't have a whole lot of ranking points to defend, there is a chance that I could reach No1.

"I am going to have to play like I did for the second part of last year. I am going to have to do the same in the first part of this year and try to be very consistent. "

The roof stayed open on centre court today despite the extreme heat as officials decided to opt for other measures to allow the players to deal with the conditions.

Murray said: "Even when you sit down at the change of ends, you are expecting to chill out a little bit in the shade, but it's roasting even when you're just sitting there. That was tough.

"If you have a long point, you can feel your feet burning a little bit. The good thing about playing on the bigger courts is there's a bit of shade at the back, as well. So, if you take your towel you can get out of the heat a little."

Murray will play Spain's Marcel Granollers in the second round on Thursday, when cooler weather is predicted to arrive. The Scot has won both their previous meetings - in 2004 at a futures event and in Barcelona on the main tour a couple of years later.

Granollers battled for more than three and a half hours to beat Russia's Teimuraz Gabashvili 6-4, 7-6, 4-6, 6-0 on Court 10 today but does not think his draining contest will affect him against Murray.

The world No51 said: "He has a lot of talent and has gained a lot of confidence from last year's results but I am comfortable on hard courts and I don't think my long game gives him an advantage."

While the Spaniard prepares to face Murray, the beaten Pavel goes home with a losers' cheque for nearly £10,000.

Although he said he was given the all-clear by a doctor to play, the Romanian did tennis a major disservice by using his protected ranking (he is the world No1140) to get automatic entry into this Grand Slam.

Pavel had hoped to appear here and then go on to play in a series of other tournaments, culminating in a farewell in Bucharest.

He admitted today: "I guess, you know, it does not always go like how you planned. The pain is still there and I don't want to try it again. I don't want to damage my health just for playing another tournament. "

Murray offered words of sympathy for Pavel. He said: "I saw Tim Henman go through a similar sort of thing. He had a lot of problems with his back towards the end of his career. He was kind of hanging on and was in a lot of pain when he was playing, but tried to play through it.

"It's obviously tough for all of the guys, but nice to try and play the Grand Slams one last time and enjoy them rather than stopping at a smaller tournament. It's a shame it had to finish like that."