Slip in ranking not a big deal for Murray

Del Potro moves up to world No 4, but the Scot is not worried about how this affects his seeding at the Australian Open.

Andy Murray's decision to play alongside English schoolgirl Laura Robson in the more relaxing exhibition environment of the Hopman Cup in Perth rather than defend his Qatar Open title in Doha last week has cost him a privileged top-four seeding position at the Australian Open.

The British No 1's surrendering of all 250 of his Doha ranking points has enabled US Open champion Juan Martin Del Potro to overtake him in the latest ATP rankings published yesterday, leaving the Scotsman vulnerable to a quarter-final clash against world No 1 Roger Federer, defending champion Rafael Nadal, the 2008 winner Novak Djokovic or Del Potro. The points margin between the Argentine Del Potro and Murray is frustratingly small at 6,785 to 6,780 but Murray knew that the fall would be a consequence of his change of policy to go to Australia much earlier this year to prepare for the first grand slam of the new campaign.

His response to the setback of being demoted to fifth seed in Melbourne was positive. "I really don't think the seedings make any difference. If you get to the quarter-finals you're going to have to beat the best players anyway," he said. "Maybe it will be one more than normal but you're banking on the top four seeds getting to the quarter-finals and you never know. There are always some surprises and I need to make sure I get there myself first."

Murray will be hoping that his different itinerary brings an improvement to his comparatively poor Australian Open record. The former US Open runner-up and Wimbledon semi-finalist is yet to progress beyond the fourth round on the hard courts of Melbourne Park. Murray left Perth satisfied with his progress after four singles and four mixed-doubles matches. "In terms of the way I struck the ball, it felt really good, so I'm happy with that. I'll get ready for the Open now, which is what I came here to win.

"I'm really, really happy with the way I was playing and I'm sure with another week of training and practising, I'll be playing better. "If I can do that, there's a good chance I can win. I think I am ready to win it," he added yesterday. Nearly all of the main contenders for the women's title in Melbourne subscribed for the high-class warm-up tournament in Sydney but that line-up has already fragmented considerably at the end of its opening day.

The fourth-seeded Caroline Wozniacki pointed to jetlag after suffering a 2-6, 6-3, 6-2 defeat to China's Na Li. "I didn't play my best game today," said Wozniacki, the Danish youngster who reached the final of last year's US Open and is well fancied to break her grand slam duck this year. She was followed through the exit door by Jelena Jankovic, who was world No 1 this time last year but has slipped to eighth in the WTA rankings race.

The Serb lost her opening round match 5-7, 6-1, 7-5 to Hungary's Agnes Szavay. "It was my first match of the season and I was a little bit nervous," said Jankovic. "I really tried my best but I wasn't playing well. I was not hitting the ball as I wanted to and not serving well either." Those casualties came after the withdrawal of former world No 1 Justin Henin, in the wake of her exhausting efforts during her comeback event in Brisbane last week, and Vera Zvonareva - the ninth-ranked Russian - who continues to struggle with her recovery from ankle surgery.

She is clearly a big doubt for the Australian Open, as is the French contender for the men's title - Gael Monfils - who withdrew from his Sydney commitments because of a problem with his shoulder, which is inflamed.