Despite winning the NAB Cup, Voss said the pre-season had no correlation to premiership matches and the Lions would have to improve "20 per cent" against the Western Bulldogs on Saturday.
He said it was up to the younger core to lead the way after making genuine improvement in the pre-season.
"We need players to come in and have career-best seasons," Voss said.
"Not so much from Jonathan Brown, but we need it from our midfield group, that 21 to 23 years of age that have that physical maturity and can stand up to contests.
"We need Billy Longer, Elliot Yeo, Mitch Golby, Patrick Karnezis, Josh Green and Claye Beams to have career-best seasons.
"It (the midfield) is an area we need to improve in our game. It hasn't been a strength of ours for two years. Results have been favourable though the NAB Cup but now you've got to do it under some serious heat."
The players Voss highlighted are all second and third-year Lions that shone through the pre-season and have added considerably to the club's depth.
Voss said to be competitive, there was an element of brutality that needed to be sustained for four quarters.
The only injury concern for the Lions ahead of round one surrounds ruckman Matthew Leuenberger.
The West Australian is recovering from an Achilles injury that destroyed his 2012 and has been treated ultra cautiously by the club during the pre-season.
Voss said he was healthy, but after just one NAB match and a half in the reserves, was underdone and only a "50-50" chance of playing.
He said there was no chance of complacency against the Bulldogs.
"NAB Cup doesn't relate to the season, it has no correlation at all and it'd be dangerous to think otherwise," he said.
"If we don't respect that, we're going to get burnt.
"I've seen a few of their games over the pre-season and they've been tough and hard and competitive. They've run some pretty good teams to the wire … and you know those guys are going to crack in.
"I think they've been pretty impressive the way they've been going about their business, and quietly really. I think the general public will not have high expectations of them, but I think the Bulldogs will have high expectations of themselves."
Michael Whiting covers Brisbane Lions news for AFL.com.au. Follow him on Twitter: @AFL_mikewhiting
