Centre-back Lescott was making his first public appearance for Albion following his move from Manchester City after recovering a calf problem, but limped off 10 minutes from time following his introduction as a half-time substitute in Saturday's 1-0 defeat.
Belgium defender Pocognoli, recruited from Hannover last month, was withdrawn four minutes from time after going down under a strong challenge at the City Ground.
Albion head coach Irvine revealed that Lescott - who featured in a behind-closed-doors friendly against Bury last month - had sustained a knee problem, while Pocognol had been struggling with a minor hip and groin niggle, but the Scotsman is hopeful neither player is facing a spell on the sidelines with the Premier League season starting in a fortnight.
Irvine told the club's official website: "I've just spoken to Joleon and he feels OK.
"He just felt something on the outside of his knee. He felt it when he was warming up and when he cleared from the corner of the pitch he felt it go.
"He says it has settled down now. He was a little bit worried about it at the time but it has settled so hopefully it's nothing too bad.
"As far as Seb is concerned, he had been complaining in the first half about being a bit tight in his groin and hips.
"We did a bit of work on him at half-time and then, of course, he got clattered going for a header.
"At that point, I just thought 'take him off'."
Albion captain Chris Brunt got his first pre-season action as he came on for the last 18 minutes, having recovered from a groin injury, and Irvine welcomed the return to fitness of the midfielder.
He added: "The positive was Chris Brunt getting his first 20 minutes or so of pre-season,
"I was pleased about that. He's come through that fine after only just starting training with us.
"He's quite a way off - but it's progress."
New signing Matt Fryatt scored the only goal of the game as Forest claimed a morale-boosting win a week before their Championship opener against Blackpool.
