OXFORD United pulled off a sensational Carabao Cup shock as they routed West Ham United at the Kassam Stadium.

Second-half goals from Elliott Moore, Matty Taylor, Tariqe Fosu and Shandon Baptiste saw off a side that came into this third-round clash fifth in the Premier League.

After an even first half United were unstoppable during the second period, with Moore’s low strike getting the U’s up and running on 55 minutes.

Substitute Taylor slotted home from close range to put the home side in charge with 20 minutes to go, as United pressed for a killer third.

It came when Arthur Masuaku slipped on the halfway line to allow Fosu a clear run at goal and he rounded the goalkeeper to score.

There was still time for Baptiste to add the cherry on top, as his calm finish sent United into the fourth round for the first time in 22 years.

United made six changes to the line-up that began Saturday’s 6-0 thrashing of Lincoln City.

George Thorne made his first start for the U’s and Moore came in after recovering from a back spasm, while Rob Hall got the nod against his former club.

West Ham predictably looked to gain control of possession from the start, but the lower-league side had the two best chances of the first period early on.

When Hall’s shot was blocked the ball ran to Cameron Brannagan 10 yards out, but the midfielder failed to make a proper connection and the ball skewed behind for a goal kick.

Moments later, the U’s should have done better again. Baptiste’s pass was collected by the onrushing Forde who sprung the offside trap, but his tame shot rolled past Roberto’s right hand post.

Thorne was beginning to impose himself on proceedings, but his night ended in disaster when he came off worse in a challenge with Carlos Sanchez after 20 minutes.

The midfielder gingerly walked off with a shoulder injury, to be replaced by Mark Sykes.

This pushed Brannagan back into the deeper role, with Sykes playing alongside Baptiste, who won a free kick on 26 minutes to present United with another chance.

Hall grabbed the ball and curled a free kick over the wall, only to be denied by the crossbar.

West Ham continued to look dangerous, but neither side went close again before the break.

When the teams emerged, United picked up where they left off and deservedly led.

A United free kick from the right was half-cleared and Sykes kept the ball alive to find Moore, who turned and rifled the ball past Roberto.

The home fans stepped the decibel level up a notch and only a brilliant save from Roberto prevented United doubling the scores just after the hour mark, as the goalkeeper tipped Mackie’s flick away from danger.

It was one of the striker’s last actions of the game, but his replacement did not take long to make an impact.

After some good work from Baptiste on the edge of the area, Sykes rolled a perfect ball across the six-yard box for Taylor to tap in.

By now the Hammers had brought on the big hitters, with £45m striker Sebastien Haller, Felipe Anderson and Mark Noble all coming on, but United continued to probe.

They got their reward with six minutes later, when Masuaku’s error allowed Fosu to sprint clear and the winger kept his cool to beat Roberto.

Ajeti was denied a consolation for West Ham by an excellent Simon Eastwood save, before Baptiste escaped his marker to race into the area and cap a night that will live long in the memory for United.

Oxford United (4-3-3): Eastwood, Long, Dickie, Moore, Ruffels, Thorne (Sykes 23), Brannagan, Baptiste, Hall (Fosu 78), Forde, Mackie (Taylor 68)

Unused subs: Stevens, Jones, Woodburn, Agyei.

Booked: Moore

West Ham United (4-1-4-1): Roberto, Zabaleta, Diop, Balbuena, Masuaku, Sanchez, Snodgrass (Noble 73), Wilshere, Fornals (Anderson 65), Holland (Haller 56), Ajeti

Unused subs: Fabianski, Cresswell, Cardoso, Coventry.

Booked: Snodgrass

Referee: Robert Jones (Merseyside)

Attendance: 10,450  (1,513 visitors)