IT may be related to the fact that Fraser Forster is simply busier when the level of opposition goes up a notch, but whatever the reason, the big occasion seems to bring the best in the big goalkeeper.

So it was when Lazio came calling on Thursday evening, with the former England number one playing just as big a part in securing a famous comeback victory as either Ryan Christie in dragging them level, or Christopher Jullien in heading home the late winner.

The whole experience left Forster visibly moved as he tried to take it all in in the aftermath of a frenzied night, but Lennon was certain that it would be these games in which Forster would prove to everyone why his manager brought him back in from the cold of the Southampton wilderness to the warm embrace of the Celtic Park cauldron.

“You need your goalkeeper,” Lennon said. “It’s nothing be ashamed of. You need your goalkeeper to play well against top opposition.

“Time and again, he’s proved that he can do that over his career – especially in his time here.

“I believe he was quite emotional after the game. It’s fantastic for him and fantastic for us.

“I think the muscle memory kicks in, when you get into that sort of arena. The environment brought the best out of him – and he made big saves in big moments. That’s why we brought him in.

“You almost get disappointed when he does concede a goal, because he’s that good.

“It’s just his presence and what he brings to the team. It was great to see that manifest itself again, having seen it here six or seven years ago.

“I think he just wanted to play. He’d been on the cusp with a couple of loans last season that didn’t come through.

“We knew there was interest from the player to come, and with Bainy (Scott Bain) having an injury for a couple of months, we needed another goalkeeper in.

“I wanted a top one, and I think we’ve got a top one in.”

Forster’s spectacular injury-time stop, as he clawed out Lazio substitute Danilo Cataldi’s peach of a volley from the top corner, grabbed most of the headlines after the game. For Lennon though, his earlier stop from Lazio skipper Manuel Parolo with the scores locked at 1-1 was even better.

“That was a brilliant save, because it was a goal all the way,” he said.

“The later one, it was such a great hit – but maybe he’s got more time to see it and get across. It was a brilliant save as well, of course. But, for me, the block from four or five yards out is immense. Absolutely immense. And then, when he saves it, the ball goes 20 or 30 yards away, as well.

“That should also be a lesson to us in the dying moments of the game. It’s frantic, players need a break because we’ve been under a bit of pressure. We should have handled that situation better, it should never have got to the volley.

“We should have played a ball over the top and it could have been 3-1, home and hosed, rather than 2-1 or even 2-2.

“It’s important that we look at it. We can’t be lax like that and invite the pressure on again.

“I said last night it was like Stuart Armstrong against England at Hampden. We fortunately got on the right side of it last night.

“But it could easily have been 3-1 with the way Lazio were throwing things at us last night.”

Unfortunately for Celtic, there are tens of thousands of reasons why it may prove difficult to turn Forster’s temporary move back to the club a permanent one come the summer, and bridging the gap to the wages he receives in the English Premiership is undeniably a huge stumbling block to that ever happening.

Lennon would dearly love to have him beyond the summer, and though he knows it will be difficult, that won’t stop him trying.

“We’re a long way off that yet,” he said. “There are so many factors in it.

“We’re grateful for the loan from Southampton. It depends on what the player wants to do and then what Southampton want to do, as well.

“So, we’re a long way off talking about that just yet.”

Lennon and his team have enough to occupy their minds in the short term, with a crucial Premiership encounter against Aberdeen at Pittodrie tomorrow lunchtime on the horizon.

He is hoping both he and his team have learned lessons from their last quick turnaround after an epic European night at Celtic Park, with the champions brought back down to earth with an almighty thump at Livingston on the back of the win over Cluj.

That’s not to say he is minded to make too many changes to a winning team, but he concedes that there may be one or two players who need to be given a breather for their own good.

“We have to learn from the Cluj-Livingston double-header,” he said. “This is exactly the same.

“We have to get them back down to earth. I don’t think that will be too much of a problem but it’s a real stiff test for us on Sunday. There’s the travelling in between as well.

“Livingston can be a difficult venue at any time. And Aberdeen is the same. It’s a really tough game for us to go into.

“We may have to rotate a little bit, I don’t know if there are any aches and pains. A couple came down with cramp and maybe a bit of fatigue there it’s something we will have to look at.

“I don’t want to make too many changes.”