Norwich City 0, MK Dons 4: Norwich City old boy Luke Chadwick returned to haunt his former employers last night with a brace in a Carling Cup humbling at Carrow Road.

MK Dons arrived top of League One and left with a deserved place in the third round after profiting from the sort of charitable defending rarely seen during Paul Lambert's Norwich tenure.

The Scot changed all 11 starters from the weekend home Premier League draw against Stoke – but the names in City's shadow side did little to advance their personal cause for a starting spot against Chelsea at Stamford Bridge this coming weekend.

Zak Whitbread played just over 70 minutes in a welcome return from the knee problem which forced him to miss Sunday's 1-1 opening home draw. The American's display was one of the few bright spots in another early cup exit for the Canaries.

Steve Morison also had a second half outing after Lambert had left the Welsh international out against the Potters with a minor groin injury suffered in training.

Dani Ayala made his full senior debut for the club alongside Whitbread at the heart of a new look City backline following the Spaniard's recent arrival from Liverpool.

Russell Martin captained a side which also featured the midfield talents of Wes Hoolahan and David Fox.

Simeon Jackson looked especially keen to impress the manager in a vibrant opening salvo from the Canadian.

Andrew Surman drove over half way from Fox's initial pass but his intended ball for the pacy striker kissed the wet turf and rolled behind. Ayala's weak intended clearance dropped for Dons' dangerman Sam Baldock in a portent of things to come, but the highly-rated striker dragged tamely at Declan Rudd.

Surman and Hoolahan combined down the left only for Fox to be crowded out on the edge of the penalty area with City dominating possession in the opening quarter.

Dean Bowditch escaped down the right but Adam Drury sensed the danger to hammer away Bowditch's low cut back.

City failed to heed the warning when moments later Stephen Gleeson fed Chadwick who calmly squeezed the ball past Rudd from 16 yards.

David Martin had to race off his line to preserve the Dons' lead when Jackson burst onto Fox's throughball but was inches from a decisive touch around the advancing keeper.

Aaron Wilbraham eased past Dean Lewington wide on the right but Jackson was on a different wavelength to his occasional strike partner with a near post dart as the ball rolled behind him.

Chadwick continued to pose problems for the Canaries – clipping a ball into a dangerous area that forced Whitbread to make a decisive intervention.

MK doubled their advantage on 28 minutes when Baldock burst clear to poke a powerful right footer beyond Rudd after Gleeson had harried Drury.

Baldock swarmed all over Ayala then checked inside to pick out his bustling partner Jabo Ibehre who was eventually subdued by Whitbread – the visitors' seemingly able to launch attacks at will.

Drury tested David Martin with a shot on 38 minutes which the purple-clad Dons' keeper confidently claimed to underline the growing belief in Karl Robinson's side.

City's main attacking weapon Jackson darted inside Gary Mackenzie in the closing stages of the half, but his rasping strike was deflected behind.

Surman's 20-yard shot clearly clipped a Dons' defender with City trying to raise themselves before the interval, but the referee incurred the wrath of the home fans when he pointed for a goal kick.

Lambert resisted any temptation to introduce reinforcements from the bench at the interval with the same personnel entrusted with trying to drag City back into the contest.

Chadwick tested Rudd from long range when he veered into a central area. Fox's free-kick summed up the hosts' lack of potency in the final third when David Martin was able to watch his right footer slam into the advertising boards.

Whitbread again proved his worth with a vital touch to foil Bowditch on another penetrative burst for the adventurous visitors. Surman finally tested David Martin with a vicious dipping half volley from 25 yards on 52 minutes which the Dons' keeper acrobatically tipped over – Whitbread's glancing header from the resulting corner flying wide.

City were now beginning to finally demonstrate some long overdue urgency, but Baldock relieved the building pressure with a tidy spin and turn which set up Gleeson who rifled well into the Lower Barclay.

Chadwick punished City just before the hour mark again with a superb exchange of passes involving Bowditch taking him into the Norwich penalty box before slipping the ball past Rudd.

Lambert introduced Morison for Hoolahan – perhaps with one eye on the considerably more important pending league trip to Chelsea.

Bowditch made way for Daniel Powell – who needed all of four minutes to cash in on Surman's wayward ball to slide a fourth past Rudd.

Korey Smith was left beating the turf in frustration when he carved Morison's cutback just wide before the Welshman brushed the side netting with City looking for some scant consolation for the die hards in attendance.

De Laet entered the fray for Ayala in the closing stages of City's brief flirtation with the competition when the big Spaniard hobbled away with a knee problem.

MK were reduced to ten men for the final moments when half-time arrival Angelo Balanta was forced to limp off with a suspected hamstring injury – manager Robinson cutting a hugely frustrated figure despite the handsome scoreline as one of his key men departed.

Tottenham loanee Adam Smith ventured forward but hammered well over in the final seconds.

Morison powered past Lewington but dragged his right-footer wide before a floating header dropped into David Martin's arms.