CELTIC have been hit by another crushing injury blow with the news Mark Wilson is the latest player to undergo surgery.

The full-back had an operation for cartilage problems in a knee and now faces a battle to return to action before the end of the season.

Manager Gordon Strachan revealed: "Mark needed to have his knee tidied up. He needs a little bit of his cartilage taken off."

Strachan is waiting to hear how long Wilson will be sidelined. But, with the only other recognised right back, Paul Telfer, terminating his contract two months early to return to his family in England, it is another damaging blow to the squad at a crucial stage of the season.

Celtic face a Scottish Cup semi-final against St Johnstone on Saturday and are struggling to cross the finishing line in the SPL title race.

In the last two games, Strachan has been forced to use Gary Caldwell at right back.

The Scotland defender - out for four months after knee surgery - did not look comfortable in Saturday's hard-fought win over Motherwell, but will again have to fill the position against Saints at Hampden this weekend.

Steven McManus is available, tie as his three-game ban is only for SPL games. He has already served two games and, after this weekend, will have to miss the match at Kilmarnock a week on Sunday, where a win would finally secure the title.

Maciej Zurawski is already struggling to to face St Johnstone after limping off at the weekend with a calf injury which might require a scan to establish the extent of the damage.

The news of Wilson's latest injury is a bitter blow to Strachan and the player, who has suffered a stop-start season of just 16 games.

Wilson, 22, started his first full season in good form. But he broke a metatarsal against Manchester United on his Champions League debut at Old Trafford in September.

That kept him out for three months. When he returned, he picked up another troublesome knock which saw him replaced again by Telfer, who postponed his planned departure.

Now, after cartilage damage was diagnosed following the recent game against Falkirk, Wilson faces another period out of action.

He joins Evander Sno in rehab, the 19-year-old having also had an operation to tidy up a cartilage he damaged playing for the Dutch Under-21 side.

Celtic are said to be unlikely to receive any compensation from the Dutch FA to cover Sno's wages while he is out.

The club submitted claims to the SFA when John Kennedy and Paul Lambert were injured on international duty.

But Dutch spokesman Rob de Leede said: "We've not offered insurance cover in the past. As far as I'm aware, without checking all our regulations, that is still the case. It's up to the clubs to cover their player."