McMullan was handed an opportunity by the club’s boss Scott Brown in a recent League One game against MK Dons and kept a clean sheet in a 1-0 win.
The 18-year-old goalkeeper has been watched by Premier League sides and Newcastle are firmly in the mix to snap him up.
They have now been joined in the hunt by Aston Villa and Chelsea, who have been impressed with what they have seen from McMullen.
However, both clubs will have to push past Newcastle as the Magpies remain favourites to capture the goalkeeper.
Fleetwood may well have to deal with approaches for McMullan when the summer transfer window swings open for business.
The League One side have McMullan locked down on a contract which has a further 12 months left to run.
Fleetwood sit a comfortable 12th in the League One standings and finish off their campaign by playing host to already promoted Ipswich Town.
