Bullard is set for a scan today after being forced off against Aston Villa at Villa Park last weekend.
Bullard had just returned to action after eight months out with a knee problem.
Boateng said: “Jimmy has been brilliant for us over the last few weeks since he came back.
“We’ve said in the dressing room we mustn’t be too negative because we don’t know the extent of the injury.
“But we showed against Everton that we are not a one-man team, when we played really well without Jimmy.”
