A long pass from the £37.1 million signing to Patrice Evra in the sixth minute lead to an Ashley Young cross that was headed against the bar by Antonio Valencia, then against Cardiff goalkeeper David Marshall by Robin van Persie, and then finally into the goal at the Dutch striker’s second attempt.
The rest of the half dragged slowly to a conclusion as United had just one more good chance, Van Persie shooting wide from a tight angle, and Cardiff went close when Jamie Noone could not turn a knock-down towards goal.
In the second half Cardiff went close when Declan John’s pull-back was just inches from Kim Bo-Kyung’s run. Moments later, Young blasted a brilliant shot into the bottom right corner of the net from outside the box after cutting in from the left.
The game was settled at that point, but Valencia brought a great save from Marshall, seeing his shot palmed onto the post.
With minutes remaining, Mata left to a standing ovation from the home crowd as he was replaced by Adnan Januzaj, the United fans clearly impressed by what they had seen.
PRE-MATCH - MATA STARTS - Wayne Rooney is on the bench but the big news is that Mata starts, supporting Van Persie on his return from injury.
6’ - VAN PERSIE SCORES - Ashley Young’s cross is headed against the bar by Valencia, and Van Persie scores with his second headed attempt.
24’ - DE GEA SAVE - Noone tries to turn the ball towards goal after a Hudson header finds him with his back to goal, but the goalkeeper clears with an outstretched leg.
34’ - VAN PERSIE MISS - Evra finds Van Persie with a reverse pass, but with Ryan Giggs calling to have the chance to shoot, Van Persie pulls his effort wide.
59’ - YOUNG GOAL - Cutting in from the left wing, Young fires in a shot from outside the box that swerves one way and then the next, a brilliant goal.
66’ - KIM CHANCE - Jones’ tackle leaves the ball to run to Kim, but his shot is straight at De Gea.
74’ - VALENCIA HITS THE POST - After dithering on the ball, Antonio Valencia shifts the ball onto his right and Marshall palms his shot against the post.
90+1’ - JANUZAJ MISS - Rooney pulls the ball back for Januzaj, but he slides his shot wide.
Manchester United have earned 1001 points at Old Trafford in Premier League history, more than any other team has managed on home soil.
Cardiff City have won none and lost seven of their last nine Barclays Premier League away games.
Cardiff have the best disciplinary record in the top flight this season with just 28 yellow cards and no dismissals.
Cardiff City have failed to keep a clean sheet in their last seven Premier League games, conceding 18 goals in this run.
Juan Mata has solved little for Manchester United. He’s a great player and may well have a great career for United, but the absence of a competent midfield highlighted just how much United will struggle until more quality is bought for the middle of the pitch.
MAN OF THE MATCH
Jonny Evans (Manchester United): No player put in an especially impressive performance, but given United’s defensive frailty this season, Evans deserves praise for leading from the back.
Man Utd: De Gea 6, Rafael 6, Smalling 6, Evans 6, Evra 6, Valencia 6, Jones 6, Giggs 5, Young 6, Mata 6, van Persie 6. Subs: Cleverley 6, Januzaj 6, Rooney 6.
Cardiff City: Marshall 6, Caulker 6, Hudson 6, John 6, Mcnaughton 6, Medel 6, Whittingham 6, Noone 6, Mutch 5, Bellamy 5, Campbell 5. Subs: Turner 6, Kim 5, Daehli 6.
MATCH IN A TWEET