And he revealed the Slovakian has a big part to play in Pompey’s promotion push.
The Blues boss underlined he feels the attacking midfielder can play a significant role for his side over the second half of the campaign.
The 24-year-old hasn’t started a league game for Cook for approaching four months.
Lalkovic has had to be content with cup outings and league cameos instead after his summer arrival from Walsall.
It’s a situation which some fans have questioned, with the former Chelsea man making some positive contributions in five early-season starts.
Cook, though, feels Lalkovic’s talents are best suited to hurting teams on the counter-attack.
But that’s a scenario which hasn’t presented itself to Pompey on too many occasions this season.
Cook said: ‘Milan was going on the other day (at Newport). He was going on to win us the game.
‘He’ll be playing. We trust Milan Lalkovic.
‘We thought he’d win us the game then, but we scored with a few minutes left. We thought Lalkovic would do something.
‘There’s a lot of talent there. In certain systems certain players play well.
‘You’ll only see Milan at his best when we score first in a game.
‘Then he can be introduced when teams are chasing us. That’s when there’s a lot more space in the games.
‘What we don’t want to do is make changes which will lead to our own downfall.
‘The more space there is the more people with the talent Milan possesses will hurt you.
‘If we score first against Hartlepool, for example, everything changes in the game. That’d be perfect for him.
‘He can start a game, of course he can, but we’re not continually chopping and changing.’
Pompey go into tomorrow’s clash at leaders Doncaster on a run of a single defeat from 10 games.
The Blues are unbeaten away from Fratton Park for three months – spanning eight games.
Although tinkering with his formula of late, Cook feels continuity has been a big factor in those results.
That means players like Lalkovic, as well as the likes of Tom Davies and Amine Linganzi, have needed to stay patient.
But Cook’s message to those men is they need to be ready to go when he calls upon them.
He added: ‘We feel the balance to the team in the last eight to 10 games has been okay.We’re doing okay, and within that the team has stayed quite similar.
‘It doesn’t mean the players outside of that aren’t good or we don’t like them.
‘They have to be actively ready to go because they will play a part. That’s a massive message to them.
‘Within the club now I feel we’re a solid team of good players. Our future signings are so important as a club.
‘It’s not just a case of changing players – it’s improvement. It’s huge. Improvement is huge.’