Costa has missed the champions-elect last four games since suffering a recurrence of a hamstring problem against Stoke on April 4.
Asked whether he would pay feature again this season, Mourinho, whose side will be Champions if they beat Crystal Palace on Sunday, said:
“There is a chance he might not. There is a chance he might not.
“If we win Sunday, I would say he doesn’t play against Liverpool [next week].
“If we don’t win on Sunday and we need points against Liverpool, I’d say he would play against them. It’s about result after result, needs and needs.
“If we don’t need, probably he doesn’t play (again). A long break? A good period of work, rather. We are preparing a good working situation for him during the holiday period where he can obviously mix the holiday with work without fear.”
When fit, Costa has been brilliant for Chelsea this season, scoring 19 goals this season, including nine in his first seven Premier League games. But the Spanish striker was bothered by hamstring issues at Atletico Madrid last season and it has to worry the Blues medical staff that they cannot get him fit
Mourinho, who has Loic Remy fit again after injury, maintains Costa is too valuable to risk if the club are able to win the League without him.
“It just it isn’t worth the risk. In this process, in the last month, if we lose a game – and we don’t want to lose a second – he will be back immediately.
“Immediately. Because the results in the last month were always victories and a draw against the team in second, we don’t need to rush. We are trying to give him maximum stability for him to be stronger and stronger. No need for any risk. Remy is back.”