Time to shine for Heart replacements

John Aloisi has challenged inexperienced Heart defenders David Vrankovic and Steven Gray to make the most of their opportunity against Wellington Phoenix.

Melbourne Heart coach John Aloisi has challenged inexperienced defenders David Vrankovic and Steven Gray to make the most of their opportunity ahead of Thursday's match against Wellington Phoenix.

Simon Colosimo and Patrick Gerhardt have formed a strong partnership in Heart's centre of defence but suspension has ruled both players out for the trip across the Tasman.

Qantas Young Socceroos U20s defender Vrankovic is set for his second Hyundai A-League start, while veteran Irish defender Steven Gray, who spent two years in the Victorian Premier League before joining Heart, will make his debut on Thursday.

And Aloisi has urged the duo to stake their claims for a permanent spot in the heart of defence.

"It's a great opportunity for David and Steve," Aloisi said.

"They've been doing very well in training and both are really looking forward to the game.

"It will be an excellent opportunity for them to put their hands up for selection and show that they are competing strongly for starting places with Simon and Patrick."

Heart will also be without Richard Garcia and Aziz Behich, with Aloisi opting to rest the Socceroos duo.

Jeremy Walker, Sam Mitchinson, Jonatan Germano and Jason Hoffman are all in contention for a starting berth.

Aloisi is expecting a tough challenge against the Phoenix, having never won at Westpac Stadium in their three-season history.

The former Australian international also singled out Jeremy Brockie, following the striker's impressive campaign to date with seven goals.

"Phoenix are a tough side to play against and they're always competitive," he said.

"Brockie is the danger man for them and we have to watch him closely."