The sales pitch for Melbourne Victory and the A-League is becoming much easier for coach Ange Postecoglou - shown as he unveiled two key international signings on Tuesday.

Chilean central defender Pablo Contreras arrived on Tuesday to train with his new teammates, just as Socceroo James Troisi was secured on a one-year loan from Italian top-flight club Atalanta.

Former Olympiakos player Contreras, 35, has played at a World Cup finals among 67 caps for his country, as well as at the Sydney Olympics and in the Champions League.

Troisi, 25, adds to a swag of attacking midfield types at the Victory, and the nine-times capped Socceroo will arrive later this week.

Postecoglou is thrilled with the depth and competition for places being created at a club he has been able to put his own transfer imprimatur on during the off-season.

As well as retaining Socceroo star Mark Milligan in the midst of English Premier League interest, Victory have also added internationals Kosta Barbarouses and Mitch Nichols ahead of the season-opening derby against Melbourne Heart on October 12.

Added to the signings of Contreras and Troisi, Postecoglou says that tells you much about his club's position in a maturing domestic competition.

"I wouldn't be embarrassed to bring any footballer through our football club. This would be the equivalent of any European club they are going to," Postecoglou said.

"I can say with a matter of pride he's going to play in front of 50,000 people in his first game (the derby).

"I can tell him he's going to be playing in front of 25,000 people every week.

"Maybe we don't, across the board, pay the wages that are on offer overseas but, in terms of where we see ourselves as a football club, we see ourselves a serious entity and the competition growing into a serious entity."

Contreras has fond memories of his month-long stint in Australia during the 2000 Olympics, in which Chile were based in Melbourne and finished bronze medallists.

He scored at the MCG in Chile's 4-1 quarter-final win over Nigeria.

His signing ramps up competition in Victory's central defence, with highly rated youngster Nick Ansell and deposed captain Adrian Leijer likely to fight for one position alongside the Chilean.

Postecoglou makes no apologies for that.

"We want to be the best in the country. You don't win championships by giving people protected status - anyone," he said.

"Everyone needs to be challenged. There's going to be competition for places all over the park.

"It sets a challenge to our whole group. No one needs to be comfortable. No one needs to be complacent.