Mullen's call for total concentration for the full 90 minutes comes after his team, having seemingly wrapped up all three points, conceded a goal in the final seconds of the game against Central Coast Mariners in the opening round of the season last Friday.

"The biggest lesson from last week was the need to concentrate right until the last minute and that is so important. I was particularly pleased with the way they played in parts last week," Mullen said.

"I thought we probably did enough to win the game but the lesson we have learnt is one of concentration, and keeping our shape because to lose two points on the last kick of the game needs to hurt."

Despite the disappointment, Mullen says his charges have remained upbeat leading up to the match with Victory, and that this week's focus has been on reiterating the positives to come out of last week's game, as well as working hard on having more conviction in front of goal.

"The focus this week has been about taking the positives out of the last game and continuing to work on those, which was our pressure on the ball when we haven't got it and our defensive work, which has been very good," Mullen said. "Now when we have got the ball we need to make our attacks count by getting numbers in the box and that's what we've worked on this week."

In his first National Youth League appearance, 19 year old defender Dane Milovanovic impressed while A-League listed midfielder Joe Costa was also prominent against the Mariners Youth, Mullen pleased with the effort from all of his charges in their opening hit out.

Now, United's Youth face another tough challenge against a Victory side that had the bye in the opening round and will be looking to get their season off to a flying start.

"I think Melbourne have kept the nucleus of last year's squad so we know that the game is going to be difficult, but the more difficult and more of a challenge the game is, the better it is for these young players to learn, so it's going to be very exciting," Mullen added.