The two-time A-League champions unveiled Chilean defender Pablo Contreras as their international marquee on Tuesday and have also signed nine-time Socceroo James Troisi on a season-long loan.

Victory coach Ange Postecoglou said Contreras' arrival challenged his squad and would guarantee they avoided becoming complacent.

Speaking in Tasmania as Victory prepare for a pre-season clash against Western Sydney on Sunday, Milligan said an improved squad was crucial to his side's chances of challenging this campaign.

"We're very fortunate in the last couple of weeks we've really had some good pick-ups," he said.

"It definitely just adds to the depth of our squad, which is very important now because the league is getting a lot stronger. A lot of teams are spending well in their talent.

"They are two quality pick-ups for us that just deepen our squad which is very important now."

Milligan said Contreras was settling in nicely while he believes Troisi, on loan from Serie A side Atalanta, will be a valuable asset.

"Troisi has been at a lot of good clubs over his career. I was fortunate enough to play with him in the Olympic side and a couple of times with the Socceroos as well. He's a quality player," Milligan said.

"He'll bring a lot of experience from his travels throughout Europe and in the way he does things as well."

Taking on last year's premiers and losing grand finalists this weekend shapes as a huge chance to gauge exactly how far Victory have come in the off-season, according to Milligan.

"They're a quality side across the park and it'll be a good yardstick for us this weekend to show us how far we've come, how much more we have to go before the season starts," he said.