Second-rower Green, 21, has been sidelined by a back problem since last season but is included in the starting line-up for Saturday’s LV= Cup tie against Harlequins at The Stoop.
Director of rugby Cockerill said: “Calum started last season by gaining important experience in senior company in the Aviva Premiership. Now he is back to fitness and he has the opportunity to push on again.”
Craig Newby has not played a first-team game since leading Tigers in the Aviva Premiership Final last May after having knee surgery during the summer.
Cockerill said: “Newbs is a quality player and a leader, as he showed for us during last season when captained the team. He commands respect and leads by example. He’s working his way back to fitness and it will be good to get him back.
“Success here has always been based on having a good squad. Having options available across the squad makes for better competition in training and on matchday and allows us to rotate players through the course of a long season.”
Jordan Crane, Kieran Brookes, Mathew Tait and Tom Youngs are among the remaining absentees from the matchday squad.
No8 Crane has been ruled out for the whole season after knee surgery, while Brookes and Tait are making progress in their rehabilitation following early-season injury and Youngs is recovering from a back problem.
“Kieran suffered a nasty foot injury back in September,” said Cockerill. “His rehab is going well but he’s still a couple of months away from a full recovery.
“Mathew Tait started the season for us but he has struggled with a groin problem. He has had an operation and is coming through his recovery. He’s working well with our medical team but it can't be rushed. We’ll make sure it is 100-per-cent right before he plays again.
“Tom had a bit of an issue with his back but he’s working well in his recovery now.”
Second-rower Louis Deacon has had surgery on the hamstring injury suffered in the win over Worcester Warriors at Christmas, while Manu Tuilagi and Toby Flood are expected to return to match fitness soon.
“Injuries are part and parcel of the game, but we’ve not had a great record on that front this season,” said Cockerill.
“For example, we just got Geoff Parling and Anthony Allen back fit when Manu and Deacs were ruled out.
“But we have a very good medical team here and they work hard with the players in the rehab phase so we know they are in the best possible condition when they come back into the squad.”