Manchester United veteran Ryan Giggs admits he can't explain his motivation to continue playing.

Speaking on his arrival in Sydney for the second leg of United's pre-season tour, it is clear he loves the game as much as he ever did.

"Crazy, aren't I?" he said.

"I'm enjoying it just as much as I did 20 years ago. It's as simple as that.

"Every year is a bonus to me. Take last year: winning the league, that feeling you have after the hard work you put in. Winning that trophy makes it all worthwhile.

"The thing about Manchester United is you have to do it all over again."