Clarke, who did not exactly pull up any trees in the first half against Charlton on Saturday, has a stomach upset and that leaves Laws with only two fit strikers to choose from.
Steve Watson is unlikely to be in contention for a recall although his presence will be missed after Wednesday's midfield was run ragged by Charlton in arguably the worst performance Laws has been in charge of while at Hillsborough.
Changes are needed from Saturday's shocker in South East London but with Clarke out along with Franny Jeffers who is still nursing a calf problem, Deon Burton and Marcus Tudgay will lead the line tonight.
Wade Small is still missing with a hamstring strain so attacking options are limited - although that could change with the proposed signing of Port Vale's Akpo Sodje - brother of Sam Sodje who is set to complete his transfer from Reading in the next 48 hours.
Laws has admitted interest in the giant striker in a bid to boost his attack although the signing of Sam Sodje will hopefully plug a massive hole in Wednesday's gaping defence.
Midfielder George O'Callaghan of Ipswich has also been linked but changes are needed as Saturday's performance was just not good enough.