Match ends, Manchester City 2, Sheffield United 0.
The referee should have stopped the game after getting in the way of a pass which led to Manchester City taking the lead on their way to victory over Sheffield United, says Blades boss Chris Wilder.
The visitors were upset Sergio Aguero's goal was allowed to stand because referee Chris Kavanagh was in the way of John Fleck who miscontrolled the ball, which allowed Kevin de Bruyne to set up the Argentine.
De Bruyne added the second as Sheffield United lost away from home for the first time since 19 January.
"I've been to see the referee and he has been honest about it. We make mistakes and I believe he made one too," Wilder told BBC Sport.
"It happened that quick and I thought he could have been helped by his colleagues a little bit.
"We talk about the new rule where if the referee touches the ball then he has to blow his whistle and stop play, so surely if he is in the way and hinders us then he has to make a sensible decision.
"He should do the sensible and correct thing. I am not saying we would have won the game, or got a result, but it changes the game."
City get the job done
City will start 2020 14 points behind Premier League leaders Liverpool after returning to winning ways on a day when the result was more important than the performance after Friday's capitulation at Wolves where Pep Guardiola's side led 2-0 before losing 3-2.
City's subdued first-half performance bore all the hallmarks of a side nursing a hangover after the dramatic events at Molineux.
Ponderous and lacklustre, they failed to register an attempt on target in the opening 45 minutes before coming good after half-time to secure a 100th Premier League win since Guardiola took charge in 2016.
Having taken the lead in controversial circumstances, City sealed the points with De Bruyne's sweeping finish past Dean Henderson.
With Benjamin Mendy and Nicolas Otamendi dropping to the bench, there was a first Premier League start for Spanish defender Eric Garcia and the 18-year-old helped City to a first domestic home clean sheet since 26 October.
Yet City were far from their best in their final game of a year which saw them claim a historic domestic treble.
Positives despite defeat for gutsy Blades
A calendar year that started with a win at Wigan in the Championship ended with a gutsy performance at the home of the Premier League champions for the spirited Blades.
The last 12 months will live long in the memory of United fans who have seen their side quickly adapt to life in England's top tier after winning automatic promotion last season.
Wilder will not allow United to stand still and, despite a first away loss since 19 January, there were positives to take from only a fifth league defeat of the season.
Lys Mousset, who has been excellent since arriving from Bournemouth for £10m, headed an early chance wide before having a goal disallowed after a video assistant referee check for offside - the fifth time this season United have had a goal ruled out by VAR in the Premier League, the most of any team.
Mousset also rippled the side netting when he should have done better while Muhamed Besic also went close before substitute Billy Sharp was denied by the woodwork at the end.
This was always going to be a testing time for the Blades. Their next game is at runaway leaders Liverpool on Thursday. As they proved against City, they will not be overawed by the occasion.
Man of the match - Kevin de Bruyne (Man City)
'No secret Sheff Utd are doing well' - what they said
Manchester City boss Pep Guardiola: "We had a short time to recover and faced a strong team. Not just mentally but physically against Sheffield United. They are good in the long balls, defending. It's not a secret where they are in the table."
On his 100th Premier League win: "Of course we proud of everything in these seasons, the incredible effort. When you think about 100 wins in 134 games it is an incredible achievement. It is nice to be alongside these big teams. It means a lot."
Sheffield United boss Chris Wilder: "We believe that it could have been different. My team were excellent against fantastic players and a world-class manager.
"The way we played out of possession was good. As always when you play the big teams when the chances come around you have to taken them. And we haven't."
Aguero's goal-den year - the stats
- Manchester City forward Sergio Aguero has scored 22 goals in the Premier League in 2019 - only in 2016 has he scored more in the competition within a calendar year (27).
- Sheffield United suffered their first away defeat in any competition since January (1-0 v Swansea in the Championship), ending a run of 18 consecutive games without a loss on the road.
- City are unbeaten in their past 38 Premier League home games against promoted sides (W34 D4) since a 2-0 loss against Reading in February 2007. Only Chelsea (43 games between 2001-2015) and Manchester United (40 games between 2002-2015) have had longer such runs in the competition.
- City's Kevin de Bruyne has been directly involved in 19 goals in the Premier League this season (seven goals and 12 assists) - only Leicester's Jamie Vardy has had a hand in more (20).
- De Bruyne has an assist in each of his past three Premier League games.
While Manchester City entertain Everton on New Year's Day (17:30 GMT), Sheffield United have an extra day to prepare for their visit to Liverpool on Thursday (20:00 GMT).
- 17De Bruyne
- 20Bernardo SilvaBooked at 59minsSubstituted forGündoganat 62'minutes
- 10AgüeroSubstituted forFodenat 81'minutes
- 7SterlingSubstituted forGabriel Jesusat 88'minutes
- 9Gabriel Jesus
- 27BesicSubstituted forMcBurnieat 75'minutes
- 3StevensBooked at 85mins
- 22MoussetSubstituted forSharpat 83'minutes
- 11RobinsonSubstituted forMcGoldrickat 59'minutes
- Chris Kavanagh
- Shots on Target
Second Half ends, Manchester City 2, Sheffield United 0.
Gabriel Jesus (Manchester City) wins a free kick in the attacking half.
Foul by John Egan (Sheffield United).
Billy Sharp (Sheffield United) hits the left post with a header from the centre of the box. Assisted by Enda Stevens with a through ball.
Corner, Manchester City. Conceded by Dean Henderson.
Attempt saved. Phil Foden (Manchester City) left footed shot from outside the box is saved in the bottom right corner. Assisted by Gabriel Jesus.
Substitution, Manchester City. Gabriel Jesus replaces Raheem Sterling.
Raheem Sterling (Manchester City) wins a free kick in the defensive half.
Foul by George Baldock (Sheffield United).
Corner, Manchester City. Conceded by Oliver McBurnie.
Attempt blocked. Riyad Mahrez (Manchester City) left footed shot from outside the box is blocked.
Enda Stevens (Sheffield United) is shown the yellow card for a bad foul.
Phil Foden (Manchester City) wins a free kick in the attacking half.
Foul by Enda Stevens (Sheffield United).
Substitution, Sheffield United. Billy Sharp replaces Lys Mousset.
Goal! Manchester City 2, Sheffield United 0. Kevin De Bruyne (Manchester City) right footed shot from the centre of the box to the bottom left corner. Assisted by Riyad Mahrez.
Substitution, Manchester City. Phil Foden replaces Sergio Agüero.
Offside, Sheffield United. John Egan tries a through ball, but Oliver McBurnie is caught offside.
Corner, Sheffield United. Conceded by Rodrigo.