Reuben Hazell is waiting to discover the extent of his knee injury sustained in Shrewsbury's 2-0 win over Torquay.
The Shrews are down to their last four recognised defenders following injuries to skipper Ian Sharps, Shane Cansdell-Sherriff and Carl Regan.
And their predicament was not helped when Hazell limped off in stoppage time on Saturday following a challenge from Rene Howe which earned United's joint-leading scorer a second yellow card.
Town boss Graham Turner said: "We may not know how Reuben is until Monday.
"It's a jarred knee, but we hope he'll be alright."