What knee injury? Rafael Nadal arrived in Melbourne and practiced on Friday ahead of the Australian Open.

The world number one is under an injury cloud ahead of the year's first grand slam after withdrawing from the Brisbane International.

However, the 16-time grand slam champion looked in decent shape as he practiced in warm conditions on Rod Laver Arena.

The sight of the Spanish superstar would surely have been a boost to Australian Open officials.

Serena Williams, Andy Murray and Kei Nishikori have already withdrawn from the year's first major.

Nadal (knee) and Novak Djokovic (elbow) are also under injury clouds.

The injury saw Nadal withdraw from the ATP Finals in London late in 2017 in the last competitive tournament he played.

Nadal and Djokovic are due to play the Tie Break Tens in Melbourne on Wednesday.