MELBOURNE didn't enter its loss to St Kilda with a complacent mindset after back-to-back wins according to Demons coach Paul Roos 

The Demons were aiming for three-straight wins for the first time since 2010 when they headed to Etihad Stadium on Saturday, but they were blown away by a Nick Riewoldt-led St Kilda and lost by 39 points.

Roos said after the Demons' shock loss to Essendon in round two that some of his team had come into the Bombers game with "big heads" following their round-one win over Greater Western Sydney.

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But he denied that was a factor in the loss to the Saints, who registered their second win of the season.

"Us and St Kilda are in really similar phases of our development. We're both trying to do similar things. They had a really good game two weeks ago and weren't as good against the Giants [last week]," Roos said after the loss.

WATCH: Paul Roos full post-match press conference

"We've had three really good weeks. I didn't sense that [complacency] during the week and even during the game there was a willingness to try and dig in.

"At times it looked like we were going to get back into it. I don't think it was a lack of effort, it was more we just couldn't get our structures right and they played really well."

After a week in the spotlight following its strong win over Richmond, Melbourne was touted to be a possible finalist in 2016. Roos said the loss to the Saints hadn't been a reality check, as "we know the reality" that both clubs were in a similar position of rebuilding.

The drubbing was Melbourne's 13th straight loss to St Kilda, and continued another hoodoo for the club with its poor record at Etihad Stadium.

The Demons have now lost 23 of their past 24 games at the Docklands and Roos admitted his match committee would need to pick the right players for the venue in the future to combat the problem.

"After the game we spoke about probably changing (the) team a little bit. And it's really difficult, because it's like pulling out a crystal ball a little bit and saying 'He's not going to play well'," Roos said.

"You learn from every loss and you learn from every experience. It's certainly a venue that's very different to the MCG, but you want to set up a game style that doesn't make any difference where you play, and we just weren't able to get any defensive pressure on today and they kicked far too many easy goals.

"We need to continue to educate ourselves as coaches."

Debutant Christian Petracca was one highlight for the Demons, with the bullocking forward/midfielder gathering 16 touches and five tackles in his first game for the club since being its prized No.2 draft pick in 2014.

Roos said the 20-year-old provided the sort of impact the club expected. "He created some goals and got involved," Roos said.

The coach also heaped praise on key forward Jesse Hogan, who kicked a career-best haul of seven goals. Roos said the performance in a losing team shows last year's NAB AFL Rising Star winner's growing maturity. 

"I think it shows how far he's come as a player. He got criticised after the Essendon game for his body language and he's really worked hard over the last month," Roos said.

"Today was a reward for that three-week effort that he's put in on the training track."