Paul Hart is sweating on the results of a scan on the ankle injury Portsmouth midfielder Niko Krancjar suffered in the win over Bolton Wanderers.
Kranjcar was stretchered off just before Pompey scored the only goal at Fratton Park on Saturday after a challenge by Gavin McCann.
The Croatia international appears certain to miss Wednesday's trip to Manchester United and Hart is concerned about the extent of the damage.
"Niko's ankle is swollen, obviously there is some ligament damage, but the degree of damage we won't know until today," Hart told The News.
"It's a blow because he's been doing really well for us and is an important part of what we are doing.
"It's a worry, longer term as well.
"He's been integral to what we have been doing and I don't think he'll be fit for Wednesday.
"You don't like to see your best players coming off and, in a smallish sort of squad, every player is extremely important to us.
"At least we've got versatile players who can come in and I think that stands you in good stead for the rest of the season.
"But we won't get the true extent until later today."