Jeremie Frimpong was at Celtic for only 18 months but it was enough to coin a catchphrase and leave £11.5m in the bank. Oh my days, indeed.

Still only 20, the full-back will return to Celtic Park on Thursday night with a feeling that the suddenness of his departure in the January transfer window prevented him from signing off on his time at Celtic.

He will be well received by the home support but as Celtic look to get their first Europa League points on board against Bayer Leverkusen there will be no love lost on the pitch.

Frimpong has been a regular for the Bundesliga side following his move to Germany but Ange Postecoglou, who never crossed paths with the player, expects that he will acknowledge the brief role Celtic had in his development.

There is a sense that Frimpong’s attacking style would have fit in with Postecoglou’s own philosophy although it will be a case of limiting his forward incursions this Thursday night.  

“He has done really well,” said Postecoglou. “He did well here in the couple of years and I think he would be the first to say his time with Celtic helped him in his career. 

“We gave him that platform on which to perform. He did so and he got a great move after it. 

“Anyone who passes through this club is part of our history and I am sure he would acknowledge that.”

Any reception that Frimpong receives from the home support who relished his enthusiasm will be consigned to the backburner when the game gets underway.

Celtic’s defeat in Seville to Real Betis in their opening group game showcased both sides of Postecoglou’s Celtic with the club’s attacking verve undone by their defensive frailty.

The likelihood is that the game will come too soon for Callum McGregor, who agreed a new five-year contract with the club on Friday afternoon, while Kyogo Furuhashi is also sidelined; both players have been fundamental to the methodology that the Greek-Australian has sought to implement.

There may well be an argument for both Ismaila Soro and James McCarthy to start Thursday’s game in a bid to offer a steelier spine to Celtic, although the suspicion is that it would deviate from the philosophy that the Parkhead manager has aligned himself to.

Certainly, though, there is a need to find a way to utilise home advantage. 

“Leverkusen are an outstanding team with great pedigree and great history,” he said. It is our first home game in the group stages and it will be a special night, I am looking forward to it. 

“I thought we played really well in Spain against Betis the other week but with their fans pushing them on you see how difficult it can be to pick up points. 

“And that is when you are playing really well. So you want to get positive results in your home games and then hopefully that sets you up to progress. 

“I think every time you play against German opposition you are in for a difficult challenge but that is why we are in this game and it is an exciting prospect for us. Leverkusen are a very strong team with some outstanding players in the group. 

“But, as I say, although we didn’t take points in our first game against Real Betis I thought we did really well and we will be looking for an impressive performance again on Thursday night. 

All the games have been challenges but the home games with the supporters in are definitely special. We have already had a couple of good ones, against Alkmaar and Jablonec. 

“Even the Midtyjlland game which came relatively early, we did really well in that game. 

“In all of them the atmosphere has been great. On Thursday, we go again against a quality opponent and I am really looking forward to it.”

Adam Montgomery has come to the fore in recent weeks with the teenager impressing at times with his forward momentum. Postecoglou’s only instruction is to build on the early first-team foundations that he has set. 

“What is important for young players like Adam is that they continue on the path that they have started,” said the Celtic manager. “He has done awfully well so far. On Thursday night we had two 19 years olds in the team because you forget that Liel Abada is only 19 as well. 

“Part of what we are trying to build is to give opportunities to young players and particularly to young players who come through the ranks here. 

“Adam is one of those and he has done really well so far. He is a good kid, he has got his head down and he knows what he needs to do to continue on his trajectory.”