Former Chelsea and Manchester United midfielder Juan Mata brushed off concerns about his fitness on Saturday, saying he was confident of making an impact with new club Western Sydney Wanderers.

The 36-year-old Spanish World Cup winner has signed a one-year deal with the A-League side after departing Japanese team Vissel Kobe, where he made just one fleeting appearance last season.

Asked about his lack of game time in Japan, Mata said it was a "long story".

"It was frustrating on a personal level, not to get as much game time as I thought I would," he added on his arrival in Sydney.

Mata said he remained fit and trained in the off-season with Danish club FC Nordsjaelland before opting to join Wanderers. 

"I feel ready to come back, really eager to be on the pitch. I feel good and confident that it's going to be a good season," he said.

"I'm very lucky to have the career that I had, but I'm still hungry for more, to keep enjoying football, to keep hopefully winning trophies with this club now."

Mata won the World Cup with Spain in 2010 and was a European champion with his country two years later.

He won the Champions League with Chelsea and the Europa League with the London club and Manchester United.