Celtic manager Neil Lennon responds by making a trio of changes as Odsonne Edouard in particularly looks exhausted.

The striker goes off along with midfielders Ryan Christie and Mohamed Elyounoussi.

On go Leigh Griffiths, Hatem Elhamed and Albian Ajeti.

Pat Bonner
Former Celtic goalkeeper on BBC Sportsound

Image source, SNS

Willie Miller
Former Scotland defender on BBC Sportsound

Aberdeen's first real bit of pressure, certainly in the second half.

A good cross from Connor McLennan and the ball falls to Ryan Hedges, but the midfielder can't connect well enough with his shot from 15 yards and it is blocked by the body of Shane Duffy.

Those Aberdeen changes come and Sam Cosgrove has run his race on his first start following long-term injury. The big centre-forward comes off along with centre-half Ash Taylor.

On go full-back Greg Leigh and forward Connor McLennan.

Aberdeen midfielder Ryan Hedges sends a low drive wide from 18 yards. It's all very frustrating for Derek McInnes on the sidelines and the manager is looking to make changes.

The game has fallen into a bit of a hole. With increasing slackness in possession, Celtic seem to have settled for a 2-0 win, while Aberdeen appear resigned to defeat and limiting the damage.

Willie Miller
Former Scotland defender on BBC Sportsound

Image source, SNS

Lewis Ferguson is booked for a latest in a series of fouls by the Aberdeen midfielder.

However, Ryan Christie is unable to make them pay with the free-kick on the edge of the penalty box.

Chances at both ends.

First, Ross McCrorie's last-ditch block denies Mohamed Elyounoussi inside the Dons penalty box.

Aberdeen race up the other end as Nir Bitton is caught in possession and, after Scott Wright cuts the ball back to Sam Cosgrove, the striker fires straight at goalkeeper Scott Bain.

You have to go back 10 years to find a time when Aberdeen have come back from two goals down to avoid defeat by Celtic.

One has a feeling that wait is about to get longer. Without Jonny Hayes on left wing-back, the victim of a late training injury, Derek McInnes' side have been picked off too easily on the wings.

Anyway, Celtic get the second half under way and look to be on their way to yet another domestic cup final.

Aberdeen manager Derek McInnes has been forced to change from his usual three-man central defence already.

He has much thinking to do at the break.

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Earlier, Rangers defeated Kilmarnock 1-0 in the Premiership and the Ayrshire side's manager, Alex Dyer, told BBC Scotland: "We worked hard, especially second half.

"We showed them a little bit too much respect because they're a good side and they're top of the league.

"I don't think we deserved to win but did enough to try and get a point. If we play like that, we'll do alright."

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Celtic have certainly responded to the critics that emerged after going four games without a win.

One of those came last Sunday in a 3-3 draw against today's opponents at Pittodrie in the league.

That results obviously gave Derek McInnes' side hope, but it has proved a false one so far as they have been second best for most of that first 45 minutes. Celtic are showing no signs of fatigue from that Europa League draw with Lille on Thursday.

Celtic are well on their way to a 35th consecutive domestic cup victory and a repeat of last season's final against Hearts.

Aberdeen made the brighter start, but a couple of half chances squandered and it's been all Celtic since.

Especially after former Dons midfielder Ryan Christie curled in a fine opener. Mohamed Elyounoussi added the second from close range a couple of minutes later and Aberdeen have shown few signs of being able to respond.

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Aberdeen are being left frustrated and on-loan Rangers midfielder Ross McCrorie sends a wild drive over the crossbar.

Derek McInnes' side will need to do better than that.

Aberdeen have recovered from that two-goal, five-minute salvo, but it is still Celtic who look the more likely to score again.

Odsonne Edouard has a chance to eye up the target from a free-kick, but his 25-yard drive is straight at goalkeeper Joe Lewis.

Willie Miller
Former Scotland defender on BBC Sportsound

It looks like Aberdeen have reverted from a three-man central defence to a back four.

Meanwhile, midfielder Ryan Hedges is needing treatment, just like the Dons' gameplan.