This was the challenge that led to Rangers' penalty.

Dundee's complaint seemed to be that any contact took place after the ball had been played.

Image source, SNS

Ryan Astley has to change his shirt after having a bloody nose. The Dundee defender has his nostrils bunged up with some cotton wool and is able to soldier on for now.

Hearts whip in a wide free-kick, which is cleared by Celtic and Marc Leonard has a follow-up effort blocked by the visiting backline.

Toni Yogane is speeding down the Dundee left and is cynically taken out by Nasser Djiga.

No argument there about the yellow card for the Rangers defender.

It is getting a bit tasty and Hearts midfielder Tomas Bent Magnusson is next in the book.

Tochi Chukwuani has had a decent full debut but he is withdrawn as Mohamed Diomande is introduced to Rangers' midfield.

Debutant Andreas Skov Olsen also makes way, with Djeidi Gassama coming on to occupy the right wing.

Rory Loy
Former Dundee & Rangers striker on BBC Sportsound

Tavernier is Rangers' top scorer in the league with six goals. Miovski and Chermiti are behind him on four.

For Rangers to find themselves where they are in the league and so close to the top, crazy given their lack of goals from forward players.

We've barely restarted and Celtic striker Tomas Cvancara is in the book for a fierce push on Marc Leonard, who is trying to block his run.

Looked a bit naughty, that.

A box office couple of minutes from the big man ends with him being subbed for Sebastian Tounekti.

Pat Bonner
Former Celtic goalkeeper on BBC Sportsound

Superb goal. Under pressure, Hearts pressing them high and they're able play it out.

We thought Cvancara was on his last legs but he makes that run and plays a beautiful ball across the six yard box.

Image source, SNS

Out of the blue, Celtic come close to restoring the lead.

Tomas Cvancara stretches to get his head to a cross and the new signing's looping header strikes the top of the crossbar and team-mate Daizen Maeda is unable to score with the follow-up.

Brian McLauchlin
BBC Sport Scotland at Tynecastle

Derek McInnes is frantically telling his players to calm down and not rush when in possession.

Meanwhile, just a few yards away, Martin O’Neil looks on a bit perplexed as to how his team are struggling to regain control.

Image source, Reuters

Rory Loy
Former Dundee & Rangers striker on BBC Sportsound

It's very hard to cast an opinion on the penalty decision itself, given that we see it once, we see it live. It'll be interesting to see it again but it was confirmed by the VAR officials that it was a penalty kick.

Simply too much pace on it for Jon McCracken, who goes the right way, gets a hand to it, but it's past him before he can claw it out of the goals.

Alexandros Kyziridis ought to fire the hosts ahead.

But the Hearts winger delays his strike just long enough for Liam Scales to put in a superb block in front of goal.

Nico Raskin fires over the crossbar but is caught on the follow through by Ryan Astley.

Referee Kevin Clancy quickly points to the spot and Dundee are incensed.

The on-field decision is upheld.

Ryan Stevenson
Former Hearts forward on BBC Sportsound

It's a minute-and-a-half of everything Celtic shouldn't have done. Maeda gives the ball away, they don't clear the cross properly.

Schmeichel should save that. I know Findlay heads it down but...

Rangers get the second half started. Who will blink first at Ibrox?

Liam McLeod
BBC Sportsound commentator at Tynecastle

Everything right now is pointing towards Hearts.

Image source, PA Media

EDIT: No team has now conceded more league goals than Celtic in the period between minute 45 and minute 60 this season.