Celtic captain Neil Lennon admits losing Roy Keane would be a huge blow to the Hoops' Champions League prospects next season.
Keane recently admitted he is considering ending his playing career at the end of this campaign due to a long-standing hip injury.
The 34-year-old former Republic of Ireland skipper, who only moved to Parkhead at the start of the year after 12 and a half years at Manchester United, is contracted to the Glasgow giants until the end of the season but said recently: "I will look at things in the summer and see how my hip is bearing up.
"I am due to go back to the hip specialist in the summer. It's important to be fair to myself and the club if it is affecting me.
"I will weigh it up then but there are no guarantees about next season, I have to say."
But Lennon, who will pick up his fourth Bank of Scotland Premier League medal in six years if the Hoops beat Hearts at Celtic Park tomorrow, urged Keane to play on as long as possible.
He said: "If Roy left it would be a huge loss for us because he has already shown his qualities.
"Hopefully we will be in the group stages of the Champions League and you can't afford to lose that type of player because there are not many Roy Keanes about.
"You don't know what's round the corner, but if you keep yourself right and fit you can keep going."
