The Sri Lanka captain will play the off-spinner, if fit, against New Zealand despite calls to rest for the potential World Cup final.
Sangakkara admits Muralitharan is not certain to start semi-final
The record-breaking off-spinner injured his knee the last time the sides met, in Mumbai last week, and then strained a quadriceps muscle in the quarter-final thrashing of England.
Some former players have suggested in the Sri Lankan media that Muralitharan should be rested from the meeting with New Zealand to ensure he is fit for Saturday's final.
However, Sangakkara says they need him now.
"Everyone is trying to get him as fit as possible and fit enough to play," the captain said. "There is no point thinking about finals and saving him for other games. This is the crunch game and if he can play, that will be great for us."
Muralitharan, who will retire from the international game at the end of the tournament, formed part of a four-pronged spin-attack against England.
If he does miss out, Nuwan Kulasekara, the seam-bowler who has a fine record against New Zealand in the past, would be his likely replacement.
"It is an ongoing assessment," Sangakkara said. "With injuries like this you have to make sure the player is comfortable playing in the match, especially in a situation like this.
"We are very much hoping he will be fine, but if he is not, it is something we will just have to get on with. We have the cover to make sure we are a competent winning side."