NEIL Lennon reckons "one or two" of Celtic's Champions League heroes will ask to leave this summer, but is hopeful Gary Hooper won't be one of them.

The Northern Irishman admits the club are in a rebuilding phase following the brutal 3-0 home first-leg defeat against Juventus in midweek which all but ends their interest in this season's Champions League.

But Lennon feels it is important to retain a rump of experienced first-team stars to ensure continuity for the next generation at Parkhead. Although the likes of Victor Wanyama and Fraser Forster won't be short of suitors this summer, Lennon spoke with Hooper and his representatives the day after the Juventus match and hasn't given up on persuading his striker to stay at the club beyond his contract expiry date of May 2015.

"We will have to rebuild I think in the summer," Lennon said. "I would say there would maybe be one or two players wanting to leave at the end of the season. Sometimes it is impossible to stop that. So we will work away to replace them or look for replacements in those areas, which again is difficult to do sometimes.

"We had a chat with Gary and his representatives on Wednesday. We are still working on the contract situation so I wouldn't say Gary would come into that bracket. But there is no guarantee on anything."

Whatever transpires in the second leg in Turin, not to mention the rest of the domestic campaign, Lennon will always be hugely proud of the class of 2012-13. But European football allows no rest.

When and if the Clydesdale Bank Premier League title is secured, Celtic must navigate three qualifying ties to return to the group stages of Europe's premier club competition next season, a qualification process due to begin as early as mid-July.

The deadline hardly helps them prepare for a recruitment process under director of football development John Park which is also potentially diminished by an increase in the TV deal south of the border, and the fact others may follow Celtic's lead and encroach on niche markets such as Israel.

"The strategy is to bring them in, develop them and sell them on," Lennon said. "I quite like doing it, but sometimes it is frustrating because you see good players wanting to go and progress their careers, and you can't stand in their way.

"Have we been fortunate or have we been good in what we have done? I would like to think it is because we have been good and I hope we can maintain that consistency and recruit players the right way.

"What I would like to do, having spoken to Alex Ferguson about the Ryan Giggs and Paul Scholes of this world, is keep a few players here with longevity who are around the club and understand the club."

Lennon is still seething about the actions of referee Alberto Mallenco in failing to penalise Stephan Lichtsteiner in particular for grappling with Hooper at set-pieces and will write to Uefa and Fifa for clarification on the subject.

Pierluigi Collina is the former's head of refereeing. "I would have been happy if Collina had refereed the game because he would not have put up with that nonsense," he said.

Lennon also defended his use of Twitter to hit back at his critics. "It is something I like doing sometimes, for the club, the supporters and a few charities here and there," he said. "You get a bit of banter on it sometimes which is a bit extreme and my missus gets a bit upset about it sometimes and takes it upon herself to fire back. But it is not really important in the big scheme of things."

Should everything go according to plan in the league, and with a view to the early Champions League start next season, Lennon would love to rest some players during the run-in and blood some of his younger squad members. And that could open the door for Tony Watt.

As it turned out, the teenager was unable to recreate the substitute heroics he performed against Barcelona, having to make do with manhandling at a corner from Arturo Vidal and getting Andrea Pirlo's jersey afterwards. Watt said. "It's going in the collection. He was a few yards away from me and I sprinted over to get it and nearly wrestled him on to the ground. He took mine, but that was probably out of sympathy."