Rafael Nadal beats Tommy Haas as Roger Federer receives a walkover

Second seed Rafael Nadal dispelled fears about his physical condition with a 6-4 6-3 6-4 win against Tommy Haas in round two of the Australian Open.

Nadal injured his right knee before the tournament but after his win he said: "I'm very happy about how it improves, I'm able to play without a problem."

Roger Federer also advanced with a walkover after his opponent Andreas Beck withdrew with a back problem.

But eighth seed Mardy Fish was upset in straight sets by Alejandro Falla.

The US number one went down 7-6 (7-4) 6-3 7-6 (8-6) as Falla set up a meeting with Philipp Kohlschreiber.

Fish fell at the same stage in 2010 and 2011, while Colombia's Falla is into round three for the second year running.

Roger Federrer  "I would have loved to have played. I'm sorry to the fans, I was ready to go - I had a warm-up hit and was focused"

Read Australia Open updates on bbc sports (http://news.bbc.co.uk/sport2/hi/tennis/16606011.stm)