Australia swimming great Ian Thorpe has tried to calm speculation he could challenge Michael Phelps’ supremacy at next year’s London Olympics, saying he is currently “not very close to where I was before”.

Thorpe is one of the most successful Olympians of all time, having won nine medals in total, including five golds, across two Games, at Sydney in 2000 and in Athens four years later. He quit the sport aged 24 in 2006 citing a lack of motivation.

But Australia’s most decorated Olympian sensationally announced he was coming out of retirement in February. However, he said the past few months had been gruelling.

“At the moment I’m not very close to being where I was before,” Thorpe, speaking at Hackney’s adiZone, a free-to-use exercise centre for children in London, said.

“I’m on track with the level that I thought I would be when we set out the timeframes when I came back but London is getting very close now and it’s a real struggle.

“Training hasn’t been easy. If it was then everyone would do it.

“On the whole I’m enjoying it but there are days when it’s a struggle. It’s really hard to do the training, especially if I’m down and I’m not swimming as well as I’d like.”

When he initially announced his return, the ‘Thorpedo’ said he was aiming to compete in relays alone, but he has since hinted at a return to individual races. That could lead to him swimming against Phelps.

The American star won eight medals, six golds and two bronze, in Athens before breaking the 36-year-old record set by Mark Spitz, another US swimming legend, for most Olympic titles by winning an astounding eight golds in Beijing three years ago.

Thorpe beat Phelps in “the race of the century” in the 200m freestyle in Athens and understands why there is such a clamour for a rematch.

“It may happen. If the Olympic gods strike and we are in the same race at London then it will,” said the 28-year-old Thorpe.