They may have seen their hopes of a top six finish extinguished by Hearts’ win over Kilmarnock on Saturday, but the visitors were well worth their victory after responding impressively to Darren Mackie’s 17th minute strike for Aberdeen.
Kenny Deuchar capitalised on a Jamie Langfield error to head his side level, before Sheridan netted a low strike five minutes later. Another mistake from Langfield allowed Sheridan to score the third with 25 minutes to go.
Aberdeen lined up for their final game before the SPL split, making just one change from the side that had been beaten by Rangers at Ibrox in midweek. Former Manchester City man Paul Marshall came in for his first start since February, replacing Sone Aluko, who dropped out completely. Davide Grassi started despite a facial injury picked up in midweek.
Full-back Danny Grainger started a ban for St Johnstone, while fellow defender Dave MacKay missed out through injury. Gary Irvine came into the defence, while midfielder Murray Davidson’s return from suspension saw Liam Craig fill in for Grainger at left-back.
The visitors settled into the game quickly, and they had the first real chance after 12 minutes when Chris Millar’s cross from the right found Deuchar in space, but he headed wide.
The Aberdeen supporters claimed a penalty when Mackie tumbled under pressure from Michael Duberry, but there was nothing in the challenge.
It was Mackie who stroked his side in front after 17 minutes. Duberry failed to clear, and Marshall slid in Mackie who sidefooted home with ease.
However, St Johnstone were level within four minutes. Langfield failed to claim Craig’s free-kick, and Deuchar looped a header into the net from 15 yards. The game was turned on its head as St Johnstone went in front five minutes later.
Zander Diamond missed his header, allowing Jody Morris to slip a neat pass through to Sheridan and he turned the ball home from eight yards, beating Langfield at his near post.
Grassi picked up the first booking of the match 10 minutes from the break, as he flew into a challenge on Irvine that did not need to be made.
Aberdeen came close to levelling three minutes before the interval, Steven MacLean forcing Graeme Smith into a diving save at his near post after Jerel Ifil’s cross.
The game remained open after the interval, but both sides were again finding clear-cut chances hard to come by.
Aberdeen were gifted an opportunity when referee Calum Murray penalised Steven Anderson for handball inches outside the area, substitute Derek Young curling the free-kick narrowly over the bar.
However, St Johnstone extended their lead after 65 minutes.
Langfield failed to deal with Deuchar’s flick from another Craig free-kick, and the ball fell kindly for Sheridan to fire into the top corner from six yards. St Johnstone keeper Smith did well to block from substitute Fraser Fyvie after Mackie’s pass.
That sparked a late flurry as the home side looked for a way back, but they could not find a way past a staunch St Johnstone rearguard, although Richard Foster sent an effort wide from 20 yards.
Teenager Jack Grimmer had a late effort for the hosts, but saw the ball spin away of the legs of a defender for a corner to leave Aberdeen just six points off the bottom of the table.
Aberdeen: Langfield, Foster, Diamond, Ifil, Mulgrew (Fyvie 72), Grassi, Marshall, Kerr, Mackie, MacLean (Young 55), Paton (Grimmer 80). Subs Not Used: Nelson, Duff, Jack, Robertson.
St Johnstone: Smith, Irvine, Anderson, Duberry, Craig, Davidson, Millar, Morris, Morais (Samuel 77), Deuchar (Jackson 90), Sheridan (Sheerin 87). Subs Not Used: Main, Rutkiewicz, Gartland, Swankie. B