MELBOURNE, Australia (AP) Even Roger Federer is excited to see if No. 1-ranked Rafael Nadal can win his fourth consecutive Grand Slam at the Australian Open.

Federer, the No. 2-seed and defending champion, says, it's unbelievable what Rafa's been able to do'' andif I get a chance I hope I can stop him.''

Nadal is bidding to become the first man in 42 years to win four straight Grand Slam tournaments, since Rod Laver did it in 1969.

Federer told a pre-tournament news conference Saturday: ``It's a very exciting Australian Open to see if Rafa can do it.''

Federer is chasing his fifth Australian Open title. He holds 16 Grand Slam titles compared to Nadal's nine.