Ole Gunnar Solskjaer became the first Manchester United manager since Sir Matt Busby to win his first four games in charge of the club last night.After convincing victories over Cardiff, Huddersfield and Bournemouth, United battled past Newcastle, winning 2-0.Romelu Lukaku and Marcus Rashford both found the back of the net in the second-half to leave the Red Devils just six points off Chelsea in fourth.It certainly wasn't a vintage performance from United, but it was a priceless three points at a tough ground.Newcastle defended deep and hit the visitors on the counter a number of times, with Christian Atsu guilty of missing some golden opportunities.There were also a few crunching tackles towards the end of the game, with tempers flaring between Jonjo Shelvey and Paul Pogba.Shelvey clattered into the back of Pogba's leg with his studs raised high, with referee Andre Marriner not even brandishing a red card.You can watch the tackle below.

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https://twitter.com/Cunneen92/status/1080577492765814795

Not nice from the English midfielder.

As Marriner saw the incident and awarded a free-kick to United, the FA will not take action against Shelvey.

And former Premier League referee Mark Clattenburg thinks he knows why Marriner opted against sending off the Newcastle man; because of fatigue.

"Andre Marriner, who failed to recognise the severity of the challenge, has had a busy Christmas period," Clattenburg wrote in the Daily Mail.

"Fatigue of all the travelling and matches may have contributed in his failure to spot that this is a red card challenge.

"Pogba knows how bad the challenge was and goes in to gain some retribution later in the match on Shelvey, which failed to even get a yellow card."

Fatigue is not often an excuse you hear with regards to officials, but it must be remembered how hectic their festive schedule was as well.

Do you think Clattenburg's reasoning is valid? Let us know in the comment box below.