Derek McInnes' side have the all-important goal but they're also leading in the other important metrics as well.

Image source, BBC Sport

Breathless stuff at Pittodrie. The hosts hold the upper hand at the break, courtesy of Sam Cosgrove's penalty - his 18th goal of the season.

Aberdeen have gone close to doubling their lead on a number of occasions while Joe Lewis has denied Alfredo Morelos and Ryan Kent blazed over for Rangers.

Image source, BBC Sport

Former Aberdeen defender Willie Miller on Sportsound: He has to look up, Max Lowe had Niall McGinn totally unmarked at the far post. The chance was there for Aberdeen to take advantage of that mistake from Ryan Jack.

Aberdeen spurn a great counter attack as Max Lowe can't find Niall McGinn and Rangers take the sting out of another promising Dons attack.

What a chance! Scott Arfield shows a brilliant piece of skill to engineer some space and dart away from Max Lowe before trying to thread the ball into the feet of Alfredo Morelos.

But Aberdeen somehow scramble clear just as the Colombian was about to pull the trigger. Brilliant skill from Arfield.

Three minutes of added time at the end of the first half.

Daniel Candeias has yet to make an impression on this Scottish Cup tie. He has a half chance but drags a shot well wide of Joe Lewis in the Aberdeen goal after latching onto a gargantuan Connor Goldson pass.

Eye-catching farepublished at 40 mins

40 mins

Aberdeen 1-0 Rangers

Five minutes plus added time remaining of a pulsating first half at Pittodrie. You can't take your eyes off this Scottish Cup tie, the sun permitting.

Image source, SNS

BBC Sportsound pundit Neil McCann: "I think Aberdeen's Connor McLennan has done a number on Glen Kamara. He's one of the up and coming players in Scotland."

Image source, SNS

Rangers launch a lightning counter and Ryan Kent scampers down the left. However, he blazes high and wide, failing to force Joe Lewis into a save.

This fascinating Scottish Cup tie is wide open. The Dons remain a goal to the good, courtesy of Sam Cosgrove's early penalty.

Willie Miller on Sportsound: Another big chance for Aberdeen, they are really pressing. Rangers are playing a dangerous game here, playing their little triangles.

Aberdeen look the likelier to score as substitute Niall McGinn has a half chance inside the box but he blazes an effort high over the bar after Graeme Shinnie's initial shot was blocked.

Image source, SNS

Greg Stewart whips in the free-kick, Scott McKenna rises... his bullet header skiffs off the top of the crossbar.

Kevin Clancy points for a corner and Rangers goalie Allan McGregor almost combusts. From the set-piece, the ref quickly blows for a foul, suggesting he knows he got that one wrong.

Image source, SNS

A free-kick for the Dons in a dangerous position as Ryan Jack is penalised for fouling Graeme Shinnie.

bringthemonjpn: Rangers lucky they have their No 1 keeper between the posts...where is the No 1 popping in goals?

Former Rangers midfielder Neil McCann on BBC Sportsound: "We've talked about how good Rangers are when they get their foot on the ball. But so far, 25 minutes in, Rangers haven't had their foot on the ball that many times."

Image source, SNS

BBC Scotland's Tyrone Smith at Pittodrie: "‘Aberdeen are winning the individual battles all over the park just now..."

BBC Sportsound pundit Willie Miller on Sportsound: That must be so frustrating for Steven Gerrard - it's clear for anyone to see that Alfredo Morelos has taken a dive. He can't control himself, anything can happen now.