Mullen's season in doubt

Young Adelaide defender Daniel Mullen is set to miss the remaining three matches of the Hyundai A-League season with a knee injury.

Young Adelaide defender Daniel Mullen is set to miss the remaining three matches of the Hyundai A-League season with a knee injury.

The 19-year-old suffered an anterior cruciate ligament strain after copping a heavy knock in the 2-0 victory over Newcastle on Friday night.

Mullen has been ruled out for the remainder of the regular season but, with Adelaide currently sitting in top spot, could be fit in time for the finals.

"He's had an MRI and it's a strain. It will be three to four weeks," coach Aurelio Vidmar said.

"It is a bit of blow, he has been a revelation for us at right back."

The Young Socceroo has made nine appearances in his debut season and was a valuable contributor during the Reds' AFC Champions League and FIFA Club World Cup campaigns.

Vidmar is yet to make a decision on who will replace Mullen for the club's upcoming fixtures, with Brazilian Alemao and experienced duo Angelo Costanzo and Michael Valkanis all a chance to come into the starting line-up.

The Reds face a tough match against the third-placed Roar on Wednesday night at Hindmarsh Stadium in a catch-up game from Round 16. A win would see Adelaide move four points clear at the top of the table with two rounds left in the season.