The teams find themselves in the relegation group with the hosts two points better off than their opponents, while both only have slender leads over the drop zone.
Match preview
After avoiding relegation from the Scottish Premiership in a playoff last season, it has been another tough campaign for St Johnstone so far this time around, with the Saints kicking off the second phase in third spot in the relegation group.
Callum Davidson's side looked to have put themselves in a relatively comfortable mid-table position in their last meeting with Saturday's opponents, as a 2-1 triumph in mid-February left them on 30 points from 26 top-flight outings, before they experienced a difficult end to the regular season.
In the remaining seven first-phase matches following that victory, the Saints failed to add another notch to their wins column while only putting three more points on the board, firstly playing out draws with St Mirren and Kilmarnock either side of a 3-0 defeat to Hearts, before suffering three straight defeats at the beginning of April at the hands of Aberdeen, Ross County and Livingston.
Davidson's men would then round off the first phase with a home contest against Hibernian, and with the game tied level at a goal apiece at the break, after Stevie May's opener was cancelled out by a Lewis Stevenson equaliser, the Saints were unable to make the most of a man advantage following James Jeggo's 48th-minute red card and eventually had to settle for a point from a 1-1 draw at McDiarmid Park.
While they will be pleased having managed to end the losing run prior to the vital second phase, St Johnstone do now find themselves just two points better off than both Saturday's ninth-placed visitors and Kilmarnock in the relegation playoff place, and they will be desperate to rebuild a cushion and avoiding facing the drop for the second straight year.
Their visitors, meanwhile, come into the contest in a vastly different trajectory, having given their own survival hopes a major boost in the weeks prior to the split of the Scottish Premiership.
Dundee United experienced difficulties throughout the first phase of the season and consistently found themselves in the bottom two, and after taking their league wins tally to five for the season with back-to-back triumphs around the turn of the year, they would endure a particularly difficult run between January and the beginning of April, going 11 Premiership matches without securing another victory, while only collecting three points along the way.
Following six straight defeats, consecutive draws and a loss to Rangers, all of which saw them fall to the foot of the division, Jim Goodwin's side were finally able to make a return to winning ways at home to Hibernian, with Steven Fletcher and Jamie McGrath on the scoresheet in a 2-1 triumph, as the latter converted a penalty in the 90th minute to seal all three points, before the Tangerines made it two in a row with a victory away at Motherwell by the same scoreline.
McGrath again wrapped up that win from the penalty spot, firing his side out of the bottom two as a result, before they rounded off the first phase with a contest at home to Livingston and recorded a third successive victory as McGrath and Fletcher were once again on the scoresheet.
Now certainly with some renewed confidence in the camp, Dundee United find themselves four points ahead of basement side Ross County in the only automatic relegation place, although with Kilmarnock only trailing on goal difference, Goodwin's men will know they cannot afford to let up and will go in search of a fourth consecutive three-point haul to leapfrog Saturday's opponents and further stretch the gap between themselves and the bottom two.
St Johnstone Scottish Premiership form:
L
D
L
L
L
D
Dundee United Scottish Premiership form:
D
D
L
W
W
W
Team News
St Johnstone will remain without attacker Nicky Clark, who has been out of action through injury since the beginning of March, while Murray Davidson should also remain confined to the treatment room.
Their line will be led by Stevie May, who has played a crucial role in the Scottish Premiership so far this season, hitting seven goals and providing six assists in 32 league appearances for the Saints.
In the supporting unit behind the lone front man, Drey Wright will likely keep his place on the right wing, while Graham Carey and Jamie Murphy are both fighting to come in on the left flank, having netted four and five goals respectively so far this term, with David Wotherspoon bound to offer further attacking support from midfield.
Dundee United will likely come into the weekend with an unchanged starting XI from the one which secured their third straight victory last time out, with Dylan Levitt, Peter Pawlett, Glenn Middleton and Liam Smith all expected to remain sidelined by injuries.
Wigan Athletic loanee Jamie McGrath will again play a key role going forward from midfield, having found the net in each of the last three matches, all of which being triumphs, to take his tally to six for the season in Scotland's top flight.
He will support experienced front man Steven Fletcher, who has moved onto eight for the season in the Premiership, alongside four assists, with three goals in their last five outings, while Ilmari Niskanen and Aziz Behich should line up on the wings with Ian Harkes again joining Craig Sibbald in the engine room.
St Johnstone possible starting lineup:
Matthews; McGowan, Gordon, Considine, Montgomery; Phillips, MacPherson; Wright, Wotherspoon, Murphy; May
Dundee United possible starting lineup:
Birighitti; Freeman, Ayina, Mulgrew, McMann; Harkes, Sibbald; Niskanen, McGrath, Behich; Fletcher