Celtic may struggle to keep stars, says Neil Lennon

Celtic manager Neil Lennon admits it will be difficult to retain the players who have impressed during the club's run in the Champions League.

Having reached the last 16, the SPL leaders were beaten 2-0 by Juventus in Turin, 5-0 on aggregate.

"There'll be players who want to progress their careers and it's a progression for us too," said Lennon.

"We want to bring in players, develop them and sell them on [for a profit]. So far that strategy's worked for us."

Three key members of Lennon's squad are nearing the end of their contracts.

Striker Gary Hooper and defender Victor Wanyama, whose deals expire in the summer of 2014, have so far rejected offers to extend their stay in Glasgow.

And midfielder Joe Ledley, who will also be a free agent next summer, has yet to open talks on his future.

"We'll have a look at things and see how players are feeling at the end of the season," said Lennon. "We have a championship to win and we're in a cup semi-final."

Trailing 3-0 from the first leg in Glasgow, Celtic started brightly in the heavy rain only for the hosts to book their quarter-final place with goals from Alessandro Matri and Fabio Quagliarella.

Gary Hooper has been linked with a move to England's Premier League

But Lennon said he was enormously proud of his players for getting this far in the tournament and knows their efforts, including a famous victory over Barcelona, will not have gone unnoticed.

"It would be a travesty for these young players not to progress their careers having achieved so much in this campaign and having played against some of the best players in the world," he explained.

"Some of them want to progress their careers maybe out of Scotland and it is difficult to stop that progression.

"We're doing our job. We're bringing these young players in, we're developing them and hopefully selling them on for significantly more than what we brought them in for."

Reflecting on the end of Celtic's European adventure, Lennon added: "It's disappointing. You always want more.

"The handicap we have is that we're probably £100m behind most of the other squads in the last 16 of Champions League.

"The difference is the quality in the final third. We had good chances again tonight and we didn't take them.

"Quality counts and that was the difference over two games. We were just a little bit short in some areas.

"Juventus are a fantastic team. They have a great work ethic about them. They maybe don't have the flamboyance of Barcelona but they work so hard for each other and have a great balance."

Lennon revealed that Efe Ambrose was disciplined for being late for training on the morning of the match but insists it was not the reason the defender was omitted from the starting line-up.

The Nigeria international missed the team bus from the hotel and had to catch up by taxi.

Ambrose appeared at half-time as Wanyama picked up a hamstring injury, while full-back Adam Matthews also suffered a similar problem.