While England sealed their spot in the knockout stages with a four-wicket win over Sri Lanka on Saturday, Malan tweaked his left groin when chasing the ball in the outfield and did not bat.
Malan is said to be hopeful about his chances of facing India at Adelaide on Thursday and is continuing treatment in a bid to be fit - but it is not expected that he will go for a scan.
England, though, seem less optimistic and will be mindful of taking any risks on the left-handed batter given the enormous magnitude of what is at stake.
If he is unable to recover, then how England balance their line-up will be a talking point as they have preferred an extra batter recently, with Moeen Ali and Liam Livingstone as low as seven in the order.
Should they stick with the same formula - and make the first change to their XI of the tournament - then Salt is the spare batter in England's 15-strong squad.
He could come in as a straight swap for Malan at first drop, although Moeen believes England's strength is they could shuffle their pack accordingly to adapt to whatever they are presented with by India.
"The great thing with this side is there's so many options, you can put Ben Stokes at three, you can put Phil Salt at three, myself or whoever, there's so many options," he said.
"Mala would obviously be a big miss because he's a brilliant player in T20 cricket and he has been over a long period of time - that's if he doesn't play, I actually don't know yet. It doesn't look great."
Chris Jordan is another alternative if England wanted to replenish their fast bowling, while he has taken crucial catches during the tournament as a substitute fielder.
But it is understood Salt's attacking instincts and the adjustments he has made to improve his game since the summer have impressed England and he is in pole position to start if Malan misses out.
The Lancashire batter earned praise from team-mate Mark Wood on Sunday as the fast bowler said: "He's been ready for a while and he's got something about him.
"He's one of the only ones that faces the bowlers (in the nets). Normally the batters like dog sticks, but he takes on the bowlers and I think he's chomping at the bit."