Ange Postecoglou says the arrival of Chilean veteran Pablo Contreras puts every member of Melbourne Victory's squad on notice, not just deposed captain Adrian Leijer.
Contreras was unveiled by Victory as their new international marquee player on Tuesday and is likely to start as a first-choice centre-back in the 2013-14 A-League season.
Promising youngster Nick Ansell or long-serving defender Leijer will partner the new arrival, but the latter player's future at the club appears under threat after he was also replaced as skipper by Mark Milligan.
Postecoglou however claimed it is not just the 27-year-old stalwart who must prove himself in the campaign ahead.
"It [Contreras' arrival] sets a challenge to our whole group. No-one [should] be comfortable or complacent," he said.
"If you ask Ado [Leijer], he loves the fact that Pablo's here. We want to be the best in the country.
"You don't win championships by giving people protected status. [To] anyone. Everyone needs to be challenged. There's going to be competition for places all over the park. We need depth. That's where we got caught short last year."
Victory had been linked with Giorgos Karagounis and Fabrizio Miccoli earlier in the off-season, and the eventual recruitment of 35-year-old Contreras as a marquee may leave some supporters underwhelmed.
However, Postecoglou is adamant the retired Chile international is exactly what the club needs if they are to progress, tipping him to have a major impact on Victory's crop of promising young defenders.
"From my perspective, I had a really narrow point of reference as to what I was looking for," he said.
"It's about understanding your own football club, where you're at. Melbourne Victory is the biggest club in the country and there's an expectation around it to be successful, so you want to be bringing in quality people.
"For us, it was pretty specific in terms of what we were looking for. We needed a quality player, but also somebody who can give us some real leadership within the group as well.
"Defensively we were probably a little light on. Last year [it] was our Achilles heel, in that we didn't have a lot of depth, once we lost Adama [Traore] we really struggled.
"We've got some really exciting young defenders in our group ... having someone like Pablo in the club, I can see their development becoming even more prominent."
Contreras is expected to join Victory on their trip to Tasmania for a pre-season friendly against Western Sydney Wanderers on Friday.