Juan Mata's quality helps Manchester United to hit their stride

As an exhausted Juan Mata left the Old Trafford pitch to a standing -ovation six minutes from full-time on his Manchester United debut, it became clear just what 37.1 million pounds can buy you nowadays. Quality, -charisma and, most importantly of all to David Moyes, the inspiration for three points that may just kick-start United's spluttering season.

The club-record signing from Chelsea did not score the goal his new supporters wished for, but an assist for Ashley Young's goal and a key contribution to Robin van Persie's in a 2-0 victory over Cardiff City was not a bad start.

And with Old Trafford buoyant for once after weeks of tension and misery, the Stretford End chanted "We are staying up" as they passed the magical 40-point mark to suggest things may finally be looking up.

With Mata making his debut, Van Persie back in the team for the first time since early December and Wayne Rooney close to agreeing a new long-term contract, there was a sense of change at Old Trafford before a ball had even been kicked against Ole Gunnar Solskjaer's team.

Moyes hinted as much in his programme notes for the game. Every trial and tribulation of his first season in charge as Sir Alex -Ferguson's successor has been written in Moyes' demeanour, but he delivered a clear statement of intent.

"I have been in this job for seven months now and I feel that I have had enough time to make my assessment," Moyes said.

"I have formulated my own opinions and I have a clear idea of what I think I need to do. We will rebuild and form another strong Manchester United team. There will be changes at the club."

Mata embodies the first phase of that change, but even though the Spaniard is more likely to help United in the attacking third than defensively, his mere presence on the pitch appeared to infuse his new team-mates with the swagger and strut they have lacked this season.

Midfielders and defenders who looked dead on their feet and devoid of ideas when Sunderland eliminated them from the Capital One Cup last week were now moving the ball freely, taking it forward and playing with the confidence expected of champions.

Van Persie's return was also key to the improved mood and the Dutch forward reminded everybody of his importance to the team within six minutes of the start. Tellingly, Mata was the catalyst, with his raking cross-field pass picking out Patrice Evra on the left before the ball was eventually crossed for Antonio Valencia to head against the crossbar.

Van Persie, displaying sharpness that belied his two months on the sidelines with a thigh injury, reacted like a cobra to head the rebound goalwards.

David Marshall parried that effort away in the Cardiff goal, but Van Persie pounced again on the loose ball to head it into the net from two yards.

The Dutchman reeled away and celebrated by blowing a kiss to the Stretford End before his team-mates, Mata included, raced across to congratulate the forward.

The reaction was part joy and part relief given United's recent run, but as their torturous January has proved, a sting in the tail is never far away and the home side lived on the edge as Cardiff attempted to cancel out their lead.

Cardiff, with Craig Noone impressing down the right, attempted to expose United's defensive frailties and captain Mark Hudson went close with a 24th-minute header that David de Gea hacked clear with his legs.

Bottom of the table and needing points to improve their survival prospects, Cardiff kept the ball and gave United nervous moments, but they could not force a breakthrough before half-time.

As United's early second-half surge amounted to nothing, with the exception of a Antonio Valencia cross that landed just behind the onrushing Van Persie, the anxiety of recent home games began to resurface as Cardiff attempted to work an equaliser.

Declan John, the Cardiff left-back, was unfortunate not to create goal for former United youngster Fraizer Campbell when he lost Rafael down the flank and pulled the ball back from the byline.

It was a testing cross, deep into the penalty area, but Campbell mistimed his run and allowed the ball to fly behind him before Evra cleared the danger.

But just as the edgy United crowd began to chant "attack, attack, attack," Young calmed nerves inside Old Trafford with a stunning goal the England winger created out of nothing.

A simple pass from Mata midway inside the Cardiff half found Young hugging the left touchline. He cut inside and drifted past Kevin McNaughton and Noone before unleashing an unstoppable right-foot shot past Marshall from 25 yards.

Young has been much maligned during his inconsistent spell at United, but he has now scored two eye-catching goals in recent weeks, with this one as spectacular his piledriver at Stoke last month.

United were not content to drift to victory. Rooney, a 63rd-minute replacement for Van Persie, sent two long-range efforts just wide of goal, while Valencia spurned a clear chance to score the third when he raced clear only to check back before Marshall saved his angled shot.

Still, after too many occasions when United have counted the cost of missed chances, the odd stray finish in a 2-0 victory could be forgiven.

For United to truly turn a corner, however, this win must be the start of things rather than another flicker of light.