"He's not with the squad now. He's unlikely to take part in the first half of the tournament. If we want to name a replacement we have to do so before the fifth game," said Ponting at a media conference today ahead of MI's lung-opener against new IPL side Rising Pune Supergiants on April 9 here.
Malinga, who took 24 wickets in 15 matches to spearhead MI's winning campaign last season after the team's initial losing streak, had hurt his knees before the World T20.
Ponting also seemed not too worried about Mumbai Indians' skipper Rohit Sharma's poor form in the WT20 and said he would be in top form over the next few weeks of IPL.
He also praised the progress made by Jasprit Bumrah at the international level after missing most of IPL due to injury in 2015.
"The last couple of months I am incredibly pleased with Jasprit Bumrah's improvement. Last season he was coming off an injury lay-off, but now he's stronger than before. What he has done for India over the last couple of months has been fantastic.