Rangers secured a third consecutive Scottish Premiership win, with Vaclav Cerny's exquisite double effectively sealing the points before Ianis Hagi's late red card.

The Czech scored either side of the interval to ensure the Ibrox side end the weekend still five points back from Celtic and Aberdeen.

Hagi, introduced at half-time to make his first appearance since last August following a contractual issue, assisted the second goal.

However, the Romanian's night ended badly, his high challenge on Benjamin Kimpioka's shin being upgraded from a yellow card after a VAR check.

Although stretched at times by St Johnstone's attacking intent in transitions and robust defending, Cerny's brilliant intervention broke the deadlock for Rangers.

Cyriel Dessers had already missed a glaring opportunity and James Tavernier had come close with a free-kick before the Czech took a grip of the game.

He saw an initial shot blocked, regathered possession and brilliantly nutmegged Sven Sprangler before executing an inch-perfect curling low shot.

It was exactly the type of moment his manager and Rangers fans will want more of.

Both sides made changes at the break. Connor Barron and Hagi came on for the hosts and Andy Kirk - in his last match as interim manager before Simo Valakari takes charge - bolstered his attacking options.

But St Johnstone could not find a way through.

Mackenzie Kirk had a header diverted behind but the contest was over when Hagi fed Cerny, he danced inside and out, and found the gap to slot in his second.

St Johnstone still had moments. Adama Sidibeh struck one just off target, then Kirk took the wrong choice allowing Butland to save.

Nicky Clark then thought he had set up a frantic finish when he slammed home an excellent finish, but was deemed offside.

The outcome was the right one despite a spirited St Johnstone effort.

This night was timely for Cerny. He repaid Philippe Clement's faith after recent criticism, particularly after his incredible miss in Thursday's 4-1 defeat by Lyon.

Cerny has an interesting start to life at Rangers. Some early promise, followed by reacting to his own fans, that miss, then deleting his Instagram account.

The winger delivered here and it could be a massive moment for him. He showed the quality he has with his goals and made a bee-line for the manager after scoring.

Cerny looks like a confidence player and this should bring some.

The half-time return of Hagi offered another option for Clement. That will be delayed with suspension to now follow. The guy just cannot buy a break, it seems.

It is another league win that might have been more comfortable with another domestic clean sheet. That eases Rangers into the international break during which they can regroup before a tricky trip to Kilmarnock in two weeks.

This was night and day from the 6-0 Celtic horror show in St Johnstone's previous outing.

The visitors showed enough to suggest positive days may come once Valakari has time to impose his approach on this team.

They demonstrated intent to hit Rangers on the break and did create a number of moments that may have brought more.

They stood firm for the most part and defended very well at times, something that will be of use if they can deliver that consistently.

A moment of real quality unlocked them and fine margins cost them a route back into the game.

Their next fixture at home to Ross County will be key as they look to kick-start a revival and fresh start.

Rangers manager Philippe Clement: "I still expect more but it's an important win and a deserved win. It's very positive that we get another clean sheet. It's important we continue in that way.

"He [Cerny] did a really good job, he was really down after Thursday. Glasgow is not easy when you miss a big chance on an important night. This is the best reaction you can have after a miserable evening."

Interim St Johnstone manager Andy Kirk: "The result was poor obviously, but there's things on the pitch the new manager will have seen that we can improve on.

"We made some mistakes and got punished - that tends to happen against the better teams, but there's a lot to work with. We will look to improve on those things and hopefully things will turn for us."