Chris Millar and Collin Samuel are both expected to miss St Johnstone's clash against the Terrors with hamstring injuries.
Samuel missed the 2-0 defeat at Inverness on Saturday after suffering an injury late in the week.
And Millar limped off before half-time at the Tulloch Caledonian Stadium.
Garry Kenneth is out but Craig Conway is available again for Dundee United.
Kenneth suffered a medial ligament knee injury in Saturday's 2-1 loss at Hearts, a game in which United were without Conway following a knock the previous week against Celtic.
United are without striker Jon Daly following his hernia operation and long-term injury-victims Mihael Kovacevic, Darren Dods (both knee) and Scott Severin (ankle).
St Johnstone (from): Enckelman, Duberry, MacKay, Anderson, Morris, Taylor, Craig, Davidson, Millar, May, Samuel, MacDonald, Novikovas, Maybury, Parkin, Caddis, Adams, Smith.
Dundee United (from): Pernis, Dillon, Van der Maulen, Watson, Douglas, Swanson, Gomis, Conway, Buaben, Armstrong, S Robertson, D Robertson, Goodwillie, Russell, Banks, Dow, Smith, Allan, Mentel.
