Confident Del Potro sets sights on No 1 spot ahead of Open

Melbourne: Juan Martin del Potro feels little has changed in his life since winning last year's US Open, though the Argentine admits he now sees himself as a legitimate challenger for the world No 1 ranking.

Having ground down Roger Federer in five sets in the New York final after thrashing Rafael Nadal in the semis, the towering 21-year-old is considered one of the favourites at the Australian Open, which begins next week.

"Well, I feel good with my tennis, I feel confident," the world No 4 said this week at the Kooyong Classic, a warm-up tournament for the Australian grand slam.

"Of course, to beat Roger in the final gives me a lot of motivation and confidence to keep trying, keep working.

"And when I go to the court with Roger, Rafa, I don't feel too much different, and that's important for the career, for the future, and of course if I want to fight for the No 1."

Del Potro went on to prove Flushing Meadows was no fluke by beating Federer on the way to a runner-up finish at the ATP Tour Finals in London in November.

"I'm still the same person... But if I'm keen in the same way, if I keep working same way in the future I will have my chance to be like [the world's best]. I hope to have a good tournament next week and then we will see."