Kilmarnock moved into fourth place in the cinch Premiership by staving off a St Johnstone comeback to win 2-1 at at rain-swept Rugby Park.

The home side’s storming start saw 18-year-old midfielder David Watson thunder in a long-distance drive in the sixth minute before veteran striker Marley Watkins doubled the lead in the 17th minute and more goals should have separated the sides at half-time.

Just after the hour mark, with no let up in the foul weather, Saints substitute Nicky Clark reduced the deficit from close range and a game that looked in Killie’s control had to be managed until the end against the rejuvenated Perth side.

Derek McInnes’s side, now unbeaten in four games, are one point ahead of St Mirren whom they play in Paisley on Wednesday, but it could have been a more comfortable afternoon for them.

St Johnstone boss Craig Levein had predicted a “scrap” but his side could have been counted out of the game before half-time.

Amid swirling wind and rain in Ayrshire the unchanged home side blew their opponents away in the early stages.

In the fifth minute Killie midfielder Brad Lyons did well to get to a terrific cross from left-back Corrie Ndaba but he headed over the bar from 12 yards.

However, the home side soon took the lead when Watson, who had scored the winner at Aberdeen earlier in the month, took a Danny Armstrong pass 25 yards out and rifled his shot past diving Saints goalkeeper Dimitar Mitov and in off the post.

Levein had brought back Ryan McGowan, Tony Gallacher, Graham Carey and Chris Kane while fit-again Clark started on the bench, but they were strangely subdued.

Watkins’ goal came when he picked up the ball on the right, played in the ever-dangerous Armstrong and when the 33-year-old took the return pass inside the box, he poked it low past Mitov from 12 yards.

Killie captain Kyle Vassell then turned a tantalising cross from Lyons over the bar from six yards when a goal looked certain.

Saints threatened for the first time in the 25th minute when Max Kucheriavyi made a yard of space for himself inside the Killie box and thrashed a shot at keeper Will Dennis, who beat it away with defender Lewis Mayo completing the clearance.

As conditions deteriorated towards the interval, Vassell sent a driver over the bar from a Watkins pass as St Johnstone’s defence again looked hesitant.

There was some surprise that Levein did not make changes for the second half but after 56 minutes, with the Ayrshire side still in control, he brought on Clark for midfielder Dan Phillips and five minutes later he made an impact.

From a Matt Smith free-kick wide on the left, Clark nipped in front of the Killie defence to knock the ball past Dennis, with a VAR checking confirming he was onside.

Killie responded and after being booked by referee John Beaton for fouling Vassell outside the box – the home fans claimed he had denied a goalscoring opportunity – Mitov tipped a Liam Polworth free-kick over the bar.

At the other end, as nerves seeped into the Killie defence, Clark tested Dennis with a low drive from inside the box before Gallacher somehow flashed a shot over the bar from a Fran Franczak cross when a leveller looked inevitable.

Dennis made a fabulous diving save from a powerful Smith volley in the 81st minute as St Johnstone kept up the pressure but the visitors steadied and in the end did enough to secure another three crucial points.