Lambert believes that Okore's acquisition will bolster his central defensive unit and imbue real competition for places, which he wants to engender throughout the team.
"He's only 20 years of age and that's good but he's also an international player at a really young age and he's played Champions League football as well, which is testament to his potential," Lambert said.
"Jores has played in big games but he's a very humble lad and he will be a really good addition to our team and to our squad. I'm pleased that we've signed a player of his stature, for he is someone who can come in and make a huge impact.
"There's a great opportunity for him here and the competition for places is something that's really important. You want to try to have that throughout the team."