Mullen injury concern

Adelaide United's Daniel Mullen suffered a knee injury during the Reds' Round 19 victory over the Newcastle Jets and will have an MRI to assess the damage on Saturday.

Adelaide United's Daniel Mullen suffered a knee injury during the Reds' Round 19 victory over the Newcastle Jets and will have an MRI to assess the damage on Saturday.

Mullen struggled through the opening stanza and sat on the sidelines after the half-time break.

United coach Aurelio Vidmar said the injury was sustained when the defender clashed with the Jets' Adam D'Apuzzo.

"Sprinting in a straight line was OK," Vidmar said.

"Soon as he needed to turn sharply he felt his knee was about to give way, so we didn't take any risks with it."

While it was a blow for the 19-year-old, the injury did give Michael Valkanis a chance to take to the pitch in his 'testimonial game'.

Vidmar said the former captain 'performed very well' in the middle of the team's defence.

"He's had a fantastic career, it was a great tribute tonight and he thoroughly deserves it," he said.