Celtic first-team coach and Scotland assistant boss Tommy Burns is undergoing treatment for skin cancer.
Burns managed Celtic in the mid-1990s
The 49-year-old former Celtic player and manager was diagnosed as suffering from a melanoma after a recent scan.
Celtic's website stated: "It goes without saying that Tommy will receive every possible support from the club and his many friends.
"Anyone who knows Tommy will be well aware of his determined and positive attitude. His doctors are optimistic."
Burns will know the results of tests within the next 48 hours, but Scotland manager Walter Smith is confident his number two will battle back from the illness.
"I am aware of the situation and feel it is a very private matter for Tommy and his family," he said.
"We have spoken in the last day or two and he is very upbeat.
"He and his family have the best wishes of all of us and, knowing the sort of guy he is, I'm confident he will be back with Celtic and Scotland as soon as humanly possible.
"Tommy is a great guy first of all and then a terrific coach and all the players and international staff are fully behind him."
Friend and former Celtic team-mate Danny McGrain also backed Burns.
"I visited him the other day and he looked great," he said.
"He seemed his chirpy and happy self but he's always like that.
"Our thoughts are with him, but nobody knows at the moment how bad things are.
"But, whatever happens, he will continue to look to the future because that's the kind of man he is."
Burns began playing for Celtic in 1974 and also won eight Scotland caps in a distinguished career which ended as player/manager of Kilmarnock.
He went on to mange Celtic, the club he supported as a boy, and steered the club to a Scottish Cup win over Airdrieonians in 1995.