League One Peterborough swept aside a youthful Watford XI in a pulsating tie at Vicarage Road to book their place in the third round of the Carabao Cup.

Hornets boss Alessio Dionisi changed all 11 starters from Saturday's Championship draw at Wrexham, handing six players their full debut and naming a back-four entirely of academy graduates.

While the hosts bossed possession and had 17 of the game's 36 shots, the visitors were absolutely ruthless as Harry Leonard scored either side of half-time, after an own-goal from James Clarridge had set them on their way.

Promising 17-year-old Bolu Shofowoke and Harrison Jones netted their first ever senior goals as Posh ran riot after the break before Mamadou Doumbia headed a consolation for the Championship side, who had been unbeaten in their opening three matches of the season.

The Watford side was the second youngest since the Pozzo family took charge more than 14 years ago, with eight of the starters aged 20 or younger and two just 17.

The Posh - who themselves made six changes from Saturday's dramatic win over Mansfield - broke the deadlock inside 10 minutes when Ben Woods slotted through for Shofowoke to blaze into space on the right and his low cross was poked into his own net by the sliding Clarridge.

Leonard lashed a powerful effort narrowly past the angle of the woodwork from 25 yards but Posh keeper Alex Bass needed to be bailed out by James Dornelly after he missed a bouncing ball, allowing Doumbia to slot towards the open goal and almost draw Watford level.

The keeper then blocked Doumbia's low header from Rocco Vata's cross moments later.

Leonard made it 2-0 from close range when Watford lost possession and a low shot from Vernon Masara on the left of the box was only parried by Daniel Bachmann, making his first appearance since January 2025 after being plagued by injury.

Jones flashed a header off target for Posh before Vata - making his first start since January - curled an angled effort across the face of goal and Martin Payero fired wide from 20 yards for the hosts.

Bachmann made a brilliant reaction save on the line as Woods lashed a low free-kick through the wall just before the break and shortly after the restart produced another instinctive stop to claw Leonard's header off the line.

However Leonard broke the offside trap to latch onto Woods' low pass and dinked a glorious finish over the keeper to make it 3-0 with his fourth goal in as many games.

It was 4-0 four minutes later when Leonard's low shot was parried by Bachmann allowing Shofowoke to slam home his first senior goal.

Jones was then released on the right of the box to lash the visitors' fifth high into the net at Bachmann's near post.

Doumbia headed one back for the Hornets in the closing stages after a brilliant run and cross from Amin Nabizada and there was still time for Williams to rattle the Hornets bar from distance and Doumbia to do likewise at the other end.