The 23-year-old joins Ricki Herbert's side after being released by Melbourne Victory and will add to Phoenix's attacking midfield options.

Cernak, who has made 21 appearances for the Victory since the start of last season, has also played for Brisbane Roar and the now defunct North Queensland Fury.

He is likely to be included in Herbert's squad for the crucial clash against Newcastle Jets in Wellington on Sunday.

"Isaka will add something attacking wise in the midfield," Herbert said. 

"He is coming to us with experience at good A-League clubs and it is an opportunity for him to stake a claim for a contract next season.

"I've always liked him and when the chance came to have him for the rest of the season I jumped at it."

Phoenix desperately need a win after sliding to the foot of the table following four successive losses including last Saturday's 7-1 mauling at Sydney.

Manny Muscat is due to return from his three-match ban for Sunday's game at Westpac Stadium but Vince Lia is suspended after picking up his fifth yellow card of the season at Allianz Stadium.

Herbert will have to decide whether or not to retain Alex Smith in the midfield with Muscat and Dani Sanchez or go for a more attacking mix that could include Cernak.

Paul Ifill could also be in line for a start after returning from his ankle injury via the bench last week.