Manchester City winger Raheem Sterling is now a complete player... as Dejan Lovren's clumsiness cost Liverpool dear in Merseyside derby

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Manchester City secured a narrow victory over arch-rivals United in the derby at Old Trafford on the weekend.

Raheem Sterling had a solid game and proved he has come of age by showing smartness to keep the ball in the corner as the final whistle neared. Meanwhile, Dejan Lovren had an afternoon to forget as his clumsiness cost Liverpool in the Merseyside clash after he gave away a penalty for Wayne Rooney to equalise.

Sportsmail's columnist MARTIN KEOWN gives his verdict from the three hotly-contested derby games this weekend.

Manchester City winger Raheem Sterling impressed during their win over rivals United

Watching Raheem Sterling keep the ball by the corner flag in Fergie Time at Old Trafford, I thought: 'This boy has become a man.'

Sterling is evidence that when a top manager such as Pep Guardiola is let loose on one of England's promising youngsters, they can turn him into a complete player.

By the end, City were toying with United, but it was not just Sterling's intelligence in running down time that impressed me. His movement off the ball was sublime and he showed such toughness. Sterling should take it as a compliment that Manchester United tried to kick him off the park. He was a thorn in their side.

This was City's most difficult fixture of the season and Sterling proved that he is a player who cannot be intimidated.

Sterling showed he has become a man under Pep Guardiola with his strong and mature display

Liverpool may feel Everton were awarded a soft penalty but Dejan Lovren paid the price for being clumsy.

If Dominic Calvert-Lewin's first touch from Wayne Rooney's lofted pass had taken the striker in behind, then Lovren would have had cause for concern.

But while Lovren lost the flight of Rooney's pass, he was still goal-side of Calvert-Lewin when he received the ball. Lovren was not in imminent danger but panicked and Calvert-Lewin was clever to wait for contact. 

I have seen this before from Lovren. When he makes a mistake, he feels he has to atone for it straight away and that can lead to another error. He needs to be more careful.

Liverpool defender Dejan Lovren gave away a silly penalty after fouling Dominic Calvert-Lewin

Lovren needs to be much more careful as he is making too many costly mistakes for Liverpool

Plenty were criticising Michy Batshuayi for having a hot water bottle on the Chelsea bench at West Ham but it was a clever idea.

Using hot water bottles is not new. Jim Paul, our kitman at Aston Villa, dished them out to subs to keep them warm 30 years ago. Now, dugouts at many grounds have heated seats. It is vital to keep warm so you do not risk injury.

I wore gloves twice in my career — once at Spartak Moscow and once on a bitterly cold day at Highbury — but wish I had done so more often.

I remember getting fouled in one game and not being able to spread my hands to break my fall because they were so cold. As a result, I badly bruised my fingers.

I have no problem with players doing what it takes to stay warm.

There's nothing wrong with Michy Batshuayi holding onto a hot water bottle to stay warm