It was the Australian winger's first goal for the club and a vital one at that.

Carney, 24, was an unlikely hero on his return to a Coca-Cola Championship team low on numbers and confidence because of injuries and poor results.

In his second spell in English football, he showed a cool head in the 42nd minute to drill a low shot beyond Ali Al Habsi following a glorious through-ball from Stephen Quinn.

Carney arrived at Bramall Lane in the summer via Everton, Oldham, Hamilton, Halifax and his native Sydney.

While he was all smiles Bolton manager Gary Megson was scowling after his team's first home defeat since he took charge.

Bolton had most of the possession in the first half and Daniel Braaten could have got a couple of goals.

He had his first chance after just five minutes only to head over the bar following a cross from El-Hadji Diouf.

United took their time to settle but Lee Bromby did try to release Shelton in the 14th minute - however Al Habsi came racing out of his goal to make the interception.

Braaten again came close a minute later when his close range effort was blocked after Stelios Giannakopoulos had headed back a cross from Diouf.

United were finding Braaten a bit of a handful at this stage and he tried a spectacular overhead kick in the 20th minute that came to nothing.

The home side swept forward in the 32nd minute and Diouf tried his luck from distance but failed to test goalkeeper Paddy Kenny.

Luton Shelton should have made the breakthrough for United after 35 minutes but headed over the bar after Lee Hendrie had flicked on a cross from Chris Armstrong.

It was a clear warning to Bolton that despite their superior status Bryan Robson's United had to be respected.

Carney then made the breakthrough but the home side hit back and Danny Guthrie tested Kenny in the 51st minute and the goalkeeper spilled his effort.

However he recovered in time to prevent Giannakopoulos taking advantage in the six-yard area.

With Bolton making so many changes - Nicolas Anelka and Kevin Davies were both absent - they were struggling to knit together as a unit in front of a crowd of 15,286.

It was United who had the edge as they had grown in confidence thanks to Carney's goal.

Hendrie released Shelton in the 60th minute but his poor cross was deflected to safety.

Diouf was then booked four minutes later when he took the legs from Derek Geary after the ball had gone.

It was the Bolton striker's last act as he was immediately replaced by Christian Wilhelmsson.

Jon Stead almost added a second in the 75th minute but cleared the bar with his effort from a good position.

Bolton continued to huff and puff. However they failed to break down a United side, who always looked dangerous on the counter, and tumbled out of the competition at the first hurdle.