José Mourinho expects Ashley Cole to prove his pedigree over the second half of the season and earn himself a new contract with Chelsea, though the Portuguese has admitted he is not certain the veteran left-back will ever again be guaranteed a first-team place at the club.

Cole will make his first appearance for the team since the defeat at Newcastle on 2 November against Steaua Bucharest on Wednesday and, like John Terry and Frank Lampard, is out of contract at the end of the season. The England defender had suffered a rib injury in the victory at Norwich in the first week of October and has played and trained in discomfort since, with César Azpilicueta, more normally a right-back, seizing the opportunity presented by his team-mate's dip in form to claim a place in the side.

The lack of involvement for a player who turns 33 later this month had appeared to cast doubt on Cole's long-term future at the club. "But I think, even if you're not playing every game and are not first-choice, like he has always been, it does not mean you are not in well condition or deserving of a new contract," said Mourinho. "I feel he's fine and I think, against Steaua, he's going to show he's fine.

"Naturally, with the evolution of the season, he will play matches. Can he recover or not 100% his position? I don't know. But play? He will always play. And he will always be a good player. Naturally he will get his contract because he's a valuable player for us. I know him well. It's easy to feel he's not happy, not comfortable with the situation.

"But the way he behaves and trains? Super professional. As always. A fantastic trainer and professional. When he's on the bench behind me, I can feel he's there to win even if he's not on the pitch. Fantastic guy, full of respect from me and all the players."

Chelsea qualified for the knockout phase even in defeat by Basel last month but still require a victory over the Romanians to win Group E. Their visitors have not won in this competition for 22 matches, stretching back to 2006, but have twice held Basel in the group and will seek to exploit Chelsea's recent defensive frailties.

Mourinho has made much play of his forwards' deficiencies – he claimed his trio of strikers shared his frustration at their paltry tally of four league goals combined this term – but at the other end he has seen his team claim a solitary clean sheet in six matches in all competitions, with three goals shipped to both Sunderland and Stoke City last week.

The management staff had scrutinised last Wednesday's 4-3 win on Wearside, picking apart each of Sunderland's goals against them, but failed to determine culpability. "Maybe you laugh but, if we trained defensive corners against the dummies at the moment, maybe one time (a dummy) would score," said Mourinho, who is expected to rest Terry and may recall David Luiz to the starting line-up after a recent knee injury.

"All the rebounds are going to the opponents, so I think the rebounds will go to the dummies, too. I didn't see defensive mistakes against Sunderland. I was analysing the game for an hour, slow motion, going over every incident, seeing what we had done wrong but we did nothing wrong. The ball was just going here or there. So I didn't want to train against the dummies.

"We are creating a lot of chances but we have to kill [off] opponents. We have to score more goals. If we don't do that, we have to be very safe in the back. But am I going to change the style and play more defensive style? No. Am I going to play David Luiz in front of the centre-halves? No.

"We go in the same direction. We will make three or four changes to our side for this game because, in certain positions, we have a very strong squad. But we need to win this game, not just to finish first but to have a good feeling with a home win and 12 points. If you told me now we'd get a point against Steaua which would see us finish first because of the other result [between Schalke and FC Basel], I don't want it. I want the feeling of winning the game."

Chelsea (4-2-3-1; probable): Cech; Ivanovic, Cahill, David Luiz, Cole; Mikel, Lampard; Mata, Oscar, Schürrle; Eto'o.

Rest of squad: Schwarzer, Blackman, Terry, Azpilicueta, Ramires, Hazard, Willian, De Bruyne, Torres, Ba.

Injured: Van Ginkel (knee).

Steaua Bucharest (4-1-4-1): Tatarusanu; Varela, Szukala, Gardos, Latovlevici; Prepelita; A Popa, Chipciu, Stanciu, Tanase; Piovaccari.

Rest of squad: Nita, Georgievski, Pintilii, Neagu, Iancu, Leandro Tatu, Kapetanos.

One booking from a suspension: Szukala, Piovaccari.

Suspended: Bourceanu.

Injured: Filip (broken leg).

Referee: G Rocchi (Italy).