Scorers: Kilmarnock - McKenzie (29), Boyd (90); St Mirren - Campbell (18)
St Mirren new boy Adam Campbell gave the visitors the lead after 17 minutes in his first start since securing a six-month loan switch from Newcastle but the 18-year-old’s strike was cancelled out when Rory McKenzie levelled for Kilmarnock just before the half-hour mark.
The second half was an open affair but neither side looked like scoring again until Boyd flashed home his 12th goal of the season to clinch the three points. The win sees Killie leapfrog their beaten opponents in the Premiership table to claim eighth place.
A quiet opening period was almost enlivened after 13 minutes as Marc McAusland’s misplaced clearance from Boyd’s cross fell to Craig Slater on the edge of the Saints box and his fierce strike came back off the junction of bar and post.
But it was Saints who made the most of their first chance 17 minutes in. Jason Naismith’s cut-back found Campbell 15 yards out. The Newcastle recruit then drew in two Killie markers before swivelling and sending a low shot past Craig Samson.
It was a perfect start for Saints’ new signing but the lead lasted just 11 minutes as Chris Johnston fed McKenzie on the corner of the box. The midfielder settled himself before firing past Marian Kello at his near post.
Saints nearly hit back as Conor Newton robbed Lee Ashcroft before squaring for Steven Thompson but Samson turned the shot away for a corner. Samson then reacted smartly as Paul McGowan’s 18-yard strike skipped up off home forward Michael Gardyne’s boot, forcing the keeper to change direction before saving.
Referee Brian Colvin turned away Saints penalty claims with five minutes of the half remaining as Naismith appeared to be flattened by Manuel Pascali as he galloped into the box. The second period began with both sides cancelling each other out in the midfield. But three minutes before the hour mark, Darren McGregor’s slip let in Boyd, however the striker ballooned his shot over the target.
Seconds later, McGregor made amends with a fantastic last-ditch tackle just as Boyd looked set to strike again after Slater sent him in on goal. At the other end, McAusland sent a header just wide, while Samson blocked Danny Grainger’s volley.
Killie boss Allan Johnston sent on 17-year-old Robbie Muirhead for Gardyne after 66 minutes. The substitute then led a four-on-three breakaway with seven minutes remaining but made a mess of his shot after combining with McKenzie as the teenager swung at fresh air. However, Muirhead regained his composure in stoppage time as he played a perfectly weighted pass for Boyd to sprint onto after beating the off-side trap and the striker kept calm as he fired under Kello to clinch the victory.
Kilmarnock: Samson, Clohessy, Tesselaar, Pascali, Ashcroft, Irvine, Slater, Johnston (Nicholson, 85), Gardyne (Muirhead, 66), Boyd, McKenzie. Subs not used: Reguero, Clingan, Winchester, McKeown, O’Hara.
St Mirren: Kello, Naismith, Kelly, McGinn (Reilly, 76),McGregor, McAusland, Newton, McGowan, Campbell, Thompson (Harkins, 85), Grainger. Subs not used: Dilo, Cuddihy, Brady, Mair, van Zanten
Ref: B Colvin