This was another disaster for Jackie McNamara and the Dundee United side he will no longer manage. The former Scotland defender, following an abysmal run of seven league games without a win, paid for it all with his job.

The Dundee United board were remaining circumspect about it, but it emerged after this capitulation at McDiarmid Park that McNamara had been dismissed. Stephen Thompson, the Dundee United chairman, is expected to issue a statement today.

It brought to a close a barren run of United form stretching back to February of this year, and just one league win in nine for McNamara’s team so far this season.

Despite having a man-advantage for 67 minutes of this match after a red card shown to the Saints goalkeeper, Alan Mannus, United missed a number of chances and allowed their hosts to dominate in crucial periods. It proved to be a heroic win for Tommy Wright and his St Johnstone players.

An early United lead from a Billy McKay penalty was justly snuffed out by two second half goals from Graham Cummins and Simon Lappin. The Saints faithful loudly celebrated their team’s success, while the United end once more turned on McNamara with venom.

This game went badly awry for United, even with their one-man advantage. McNamara’s side certainly had chances, and could have been 2-0 up prior to St Johnstone pulling level, but the visitors allowed 10-man St Johnstone to shape the destiny of this match.

“I’m baffled we could lose a game like that,” said Simon Donnelly, the United assistant manager. “They bullied us at times. It is criminal what we have done.”

Wright was euphoric after this triumph and paid his players the ultimate compliment. “I’ve been here nearly four years and I rate that as one of the best performances my team has given me,” said the St Johnstone manager. “We kept two players up after our red card and we fully deserved the win.”

There had been various skirmishes around either goal before 24 in minutes when United took the lead. The build-up to that penalty converted by McKay was a terrible piece of self-harming by St Johnstone and Tam Scobbie.

The Saints defender’s attempted header back to Mannus was slow and allowed McKay to steal in on goal and prod the ball past the advancing goalkeeper. Mannus missed the ball completely and clattered into McKay, leaving referee, Bobby Madden, no option but to produce a red card.

St Johnstone sacrificed Michael O’Halloran and brought on replacement keeper Zander Clark, but it made no difference. No sooner had Clark arrived between his sticks and McKay was coolly placing his penalty inside his right-hand post.

The incident had a decided effect on this game, and not one to please the neutrals. We were denied the opportunity to watch O’Halloran’s skills, although the striker had already been hobbling after an early knock. It allowed United, in the opening half at least, to stretch St Johnstone’s new 4-3-2 system.

St Johnstone duly began the second half on fire. First, a Cummins shot flew into the chest of Luis Zwick, and then Steven MacLean, eight yards out, dunted his shot over the bar.

McNamara threw on Mario Bilate and Ryan Down after 58 minutes. Bilate missed a golden chance in front of goal from Spittal’s cross, and St Johnstone grabbed their thoroughly merited equaliser.

Liam Craig’s corner was swung to the far post, where Cummins headed the ball in under the bar behind Zwick.

St Johnstone sealed this fine win 10 minutes from time, with Lappin stealing in behind the United defence and lobbing Zwick from a tight angle.