Wellington Phoenix boss Ufuk Talay believes the loss of midfielder Clayton Lewis to a long-term injury won't knock his side off course in their bid for an A-League Men finals finish.

Lewis, who has played in every Phoenix game this season, sustained a fractured patella in last week's win over the Central Coast Mariners.

The midfielder played on in the second half against the Mariners before being substituted.

The injury is likely to force the Kiwi international to miss the next two to three months, starting with Saturday's encounter with Perth Glory in Palmerston North.

"I'm disappointed for Clay," Talay said.

"I thought he was getting some good form and created that partnership with Alex (Rufer) in that midfield.

"I believe we've got the best (number) sixes in the competition to be honest.

"We've still got Nico (Pennington), Steven (Ugarkovic) can step in and do a job.

"In these circumstances where bad things happen opportunities arise for other players to step in."

Talay said despite Lewis's injury his side was still in the hunt for a central defender.

"We're still looking at the moment and we haven't come to a conclusion," he said.

"Hopefully we can get something across the line before the window is closed."

Wellington are undefeated in their last six games against Perth and a victory will strengthen their hopes of finishing in the top six.

Perth have struggled on their travels, picking up just one win from seven away trips.

"The aim was to make the top six and we take it game by game," Talay said.

"We are playing against a very good opponent who have picked up a lot of points at home.

"They are three points behind us and the competition is still very close.

"So for us our focus is to win the game against Perth and get the three points (and) we want to finish as high as we possibly can."