And the Pompey boss backed the attacking talent to have a massive impact on his team’s run-in.
Roberts has now made six appearances for the Blues since returning from two months out with an ankle injury.
The 31-year-old has started the past three games after three appearances off the bench.
Roberts played a big role in seeing off former side Ipswich in the FA Cup to set up today’s fourth-round clash with Bournemouth.
But, by his standards, the Scouser had a quiet game in last weekend’s promotion battle loss to Oxford.
Cook batted away the suggestion he will have to treat Roberts with kid gloves after being sidelined.
The manager underlined his conviction he will have a seminal role to play over the remainder of the campaign – including today’s Cherries game.
Cook said: ‘Gary’s getting fit and he’ll play.
‘He’ll be massive over the next 20 games, or however many there will be left.
‘Gary’s a new signing for us. I’ve not got to worry about Gary Roberts, that’s for sure.
‘He got looked after in the Ipswich game knowing last Saturday was coming.
‘Gary will play games and knock games out, no problem.
‘He’ll keep going.
‘Everyone isn’t going to play well every week.
‘We’re not stupid. We’re not going to win every game, the last however many we have to go.
‘But, if we keep playing as we are, the likelihood is we’ll win more than we’ll lose.’
Roberts played through the pain last year before stepping out of the first team with his ankle issue.
Michael Doyle has soldiered on with a knee problem, while Christian Burgess returned last week in the Cup replay with Ipswich after five week out.
Cook feels their attitudes speak volumes about his players.
He said: ‘Christian Burgess got 85 minutes against Ipswich on memory.
‘You can get 70 minutes in any game on memory.
‘The fit ones can do it on repetition and memory.
‘Michael Doyle can just knock them out. The younger lads have to learn that.
‘Michael is just a tough man. He goes against the grain in modern-day football, that’s the reality of it.
‘You hear stories about Premier League teams, certain players and their clubs question if they even want to play. How sad’s that?
‘That’s the way the game’s going. That’s the reality of the game.
‘We’re lucky to have Michael Doyle.
‘Our young lads have a toughness, too. Conor Chaplin and Marc McNulty have a toughness.
‘They will always go up against centre-halves and have that toughness. They’ll never shirk anything.’