Saints have not played since the 2-0 home victory over Kilmarnock on March 9 and defender Tam Scobbie and midfielder Gary Miller have both recovered from ankle problems since then.
Defenders Frazer Wright (Achilles) and Steven Anderson (ankle) have also both had the chance to rest niggling injuries.
Midfielder Patrick Cregg returns from suspension but long-term absentees David Robertson and Jamie Adams are both still out.
United midfielder Gary Mackay-Steven faces a race against time to make the trip to Perth after picking up a hamstring injury on Scotland duty.
John Rankin remains suspended for the Tangerines but his fellow midfielder Willo Flood returns from a ban.
Striker Johnny Russell (broken leg) and defender Gavin Gunning (knee) remain on the sidelines.
United, who drew 0-0 at McDiarmid Park back in September, were last in action on March 17 when they were held to a 1-1 draw by 10-man Dundee at Tannadice.