Colchester United keeper Richard McKinney made three major errors as Steve Howard's hat-trick helped Luton to a 5-0 win at Layer Road.
U's were on a crest of a wave after winning 3-0 at Cardiff on Saturday, but they were brought down to earth with a bump by the Hatters.
Howard set the ball rolling with his opener on 14 minutes. He stabbed home a low cross from the left delivered by Peter Holmes.
Luton doubled their tally in the 21st minute when Carl Griffiths pounced on McKinney's first error of the afternoon.
The Irishman dropped Howard's cross and Griffiths swept the ball into an empty net for his first goal in 18 months.
In fact, it was only Griffiths' second comeback match since he broke his leg a year and a half ago.
Colchester had one chance to pull a goal back before Luton bagged two more before half-time.
The chance arrived on 31 minutes when Karl Duguid flicked on a long through ball by debutant Greg Halford, only for Scott McGleish to head against the bar.
Luton made it 3-0 in the 43rd minute. McKinney dropped a free kick delivered by Sol Davis and Griffiths was on the point of firing home when McKinney brought him down for a blatant penalty.
Up stepped skipper Kevin Nicholls to bury the penalty, and there was still time in the first half for Howard to nod home Luton's fourth from a cross from Nicholls.
Colchester had most of the play in the second half but they could not find a way past rookie Keeper Rob Beckwith, who was making only his second senior appearance.
Beckwith saved well from McGleish, and then tipped an attempted lob by substitute Thomas Pinault over the bar.
Yet it was Luton who found the net again with their fifth goal in the last minute of normal time.
Keeper McKinney raced out of his penalty area to collect the through ball, but he was beaten to it by Howard, who rounded United's custodian before slotting into an empty net.