Goals from debutant Kris Commons, Charlie Mulgrew, Thomas Rogne and an Anthony Stokes penalty put Celtic four ahead inside 34 minutes and on their way to the Co-operative Insurance Cup final.

Lennon was disappointed but not surprised that his side could not keep up the momentum in a second half in which Scott Vernon scored the only goal.

But his main worry was Rogne's strained calf, which forced Celtic to finish the game with full-backs Mulgrew and Mark Wilson in central defence.

Lennon now expects the club to step up their attempts to sign a new centre-back before Monday night's transfer deadline.

But overall it was a highly pleasing day for Lennon, whose first final as Celtic manager will come against Motherwell or Rangers on March 20.

"I'm thrilled," Lennon said. "It means a lot to me, obviously, it means a lot to the club and I know it means a lot to the players.

"The performance in the first half was the best I have seen from a Celtic team at Hampden in my time. They were exceptional.

"It was very hard to replicate that in the second half. The tempo in the first half was fantastic, they followed on from Wednesday night (the 4-0 win over Hearts), and if they keep that up they are going to be very difficult to stop."

However, Rogne went off on the hour mark to leave Lennon with a potential crisis ahead of their next game against Aberdeen, at Pittodrie on Tuesday.

Glenn Loovens and Daniel Majstorovic are out injured and both Darren O'Dea and Jos Hooiveld are on loan to leave Lennon hoping chief executive Peter Lawwell can sign another defender soon.

"He (Rogne) was feeling his calf," Lennon said. "He may have a calf strain so we'll see how he is tomorrow.

"The club have been pretty diligent in trying to get a centre-half in. "That will just reinforce their efforts to get one in who we have identified. We hope we can cross the line."

But he added: "I'm not (optimistic), there are no guarantees about anything at this stage of the season. "Clubs want to hang on to their players because they are either going for promotion or trying to avoid relegation or win trophies, so it's difficult."

Lennon again refused to rule out another bid to buy Kelvin Wilson, who has signed a pre-contract deal with the club. "We might go again but Nottingham Forest have been pretty firm so far in that respect and I can understand that, they are going very well in the Championship," he said.

Lennon was delighted with his most recent signing, Commons, who insisted his goal was deliberate after what appeared to be a cross sailed over Jamie Langfield's head and into the top corner.

Lennon said: "Everyone saw his attributes. He scored a goal, he was a constant thorn in Aberdeen's side, very intelligent with the ball. "He can pick a pass, showed good feet and he linked up well with (Emilio) Izaguirre, and defensively did his job very well."

Aberdeen manager Craig Brown apologised to the club's fans for their first-half display.

The Dons support came in large numbers and optimistic mood following their resurgence under Brown, but more than a few left before half-time, some throwing their scarves on to the track on their way.

It was Aberdeen's first Hamdpen visit since their Scottish Cup semi-final defeat by Queen of the South in 2008 and proved just as disappointing.

Brown said: "The main message for me is an apology to the fans. We are as upset as they are but we are conscious of the fact it's costly for them to come here."

Brown started with a three-man central defence before Nikola Vujadinovic came off with a strained calf before the fourth goal, but the Dons manager claimed the formation was irrelevant.

"We gave ourselves an impossible task," he said. "I think the first goal was fortunate,he looked as though he was trying to cross it.

"Then we didn't defend high balls and the penalty kick was a penalty kick.

"You can look at each goal and find fault, it was nothing to do with the shape."

Brown added: "The message at half-time was to win the second half. To the lads' credit, we managed to do that and with the chances we had we might have taken it into extra-time.

"But a fightback is relatively easy, it's hard for a team that's four up to maintain the momentum."