Cup finalists collide
The Scottish Cup finalists clash in a top-six league encounter at McDiarmid Park.
Midfielder Paul Paton and full-back Andrew Robertson are both doubtful for the visitors, who meet their neighbours in next month's showpiece occasion at Celtic Park.
Meanwhile, central defensive pair Calum Butcher and Curtis Good are already restricted to the sidelines.
"Right through the team we have some very good players, so you would be hoping we'd be up in a top-four spot," United midfielder Ryan Gauld told BBC Scotland. "I think it's as good a squad as there has been in previous years. So the high standards were still there, expecting to do well in the cups and get a top-six finish."
Saints are without suspended midfielder Chris Millar while Gary McDonald, Lee Croft, Tam Scobbie and Murray Davidson similarly miss out.