Roland Idowu's retaken penalty on 99 minutes secured all three points for St Mirren after a dramatic finale against St Johnstone at McDiarmid Park.

Mark O'Hara's initial spot-kick was saved but goalkeeper Josh Rae was off his line, allowing Idowu to slam in the second attempt.

Killian Phillips slotted the visitors ahead after 10 minutes but they could not add to their tally before the interval.

St Johnstone woke up in the second period when captain Nicky Clark set up Mackenzie Kirk before Benjamin Kimpioka put the hosts in front.

Teenager Evan Mooney equalised with his first St Mirren goal on 88 minutes before the Paisley side were awarded a penalty for a handball deep into stoppage time.

St Mirren move into the top six, although Dundee have a game in hand, while the Perth side remain in 10th.

Most of the chances in the first half fell the way of St Mirren, the most notable a lovely cross into the box from Conor McMenamin which just missed the feet of Greg Kiltie. St Johnstone's only real effort came in the form of an Adama Sidibeh header which floated over Ellery Balcombe's goal.

Despite a good start to the second half for St Mirren, it was St Johnstone who struck first to level things up when Kirk fired low past Ellery Balcombe.

The visitors were dealt a further blow when defender Richard Taylor had to be carried off on a stretcher before Kimpioka put St Johnstone ahead with a neat finish from Drey Wright's exquisite pass in behind.

Mooney then grabbed his first senior goal with a lovely volley but there was more to come.

St Mirren were awarded a penalty when an Idowu shot struck the arm of Jason Holt, who had turned his back on the ball, after referee Euan Anderson had allowed play to go on following a blatant shirt-pull on Toyosi Olusanya from Jack Sanders.

After a lengthy delay, O'Hara's spot-kick was saved but the video assistant referee spotted Rae leaving his line to cut the home celebrations short.

With the Buddies captain apparently injured, Idowu took the ball from O'Hara and stuck the spot-kick in the back of the net.

The reaction from Stephen Robinson at the full-time whistle proved just how crucial this victory could prove to be in deciding whether or not St Mirren finish in the top six.

They sit in sixth spot for now, two points ahead of Dundee who travel to Ibrox next weekend.

The first half performance will have been exactly what Robinson wanted, attacking intent, creating chances but just unable to turn them in - and that was punished by Kirk's second-half equaliser.

It looked to be even worse for Robinson's men when Kimpioka struck.

But they rallied impressively and when Mooney made sure it would be a day to remember St Mirren did not stop, pushing all the way to the final whistle.

It was a poor opening 45 minutes from Simo Valakari's side who failed to create any real opportunities.

A much better start to the second period got St Johnstone back on level terms and then in front.

But their attacking intent, instead of focusing on seeing out the match, probably cost them the victory as they stay stuck in the danger zone at the bottom end of the Premiership.

St Johnstone manager Simo Valakari: "We started very badly, it was my fault I put three strikers there.

"At half-time we were able to talk and change a couple of positions then in the second half it was very good. We scored two beautiful goals.

"We needed to have cool heads, at 2-1 we still wanted to push instead of seeing the game out then we lose the whole match which is disappointing."

St Mirren manager Stephen Robinson: "I have to credit the players because after the second goal it's easy to crumble.

"Last week we questioned the organisation and the desire to defend the box and be clinical at the other end. We proved that today and got a little bit of luck with the penalty having to be re-taken.

"We deserved a little bit of luck today with our first half performance and our response to going 2-1 down."