West Ham came from behind to dump Pompey out of the Carabao Cup.

Adrian Segecic gave the impressive Blues a first-half lead, before two quick-fire goals before the break and further effort after the restart saw the home side progress with a 3-1 success.

John Mousinho’s side were good value as they went in front in the 33rd minute, but the relegated Premier League side turned up the heat with a double from Valentin Castellanos and deflected Jarrod Bowen finish.

Rocco Shein was the standout Pompey performer on his competitive bow, as the Estonian produced a classy showing.

But there was the blow of another injury as Thomas Waddingham was withdrawn, after being introduced in the second half.

Pompey flew out of the blocks and applied early pressure, with Colby Bishop played clear by Adrian Segecic in the sixth minute - but the striker was penalised for a foul on Konstantinos Mavropanos.

The Blues were racking up the corners, but not threatening nearly enough from them.

That changed in the 33rd minute, however, when the impressive Shein’s delivery was cleared to Segecic who fired home from more than 20 yards via a deflection off Max Kilman.

That sent the away fans into rapture, with Shein then driving forward and forcing a save out of Mads Hermansen with a 30-yard drive.

The game swung the way of the home side in two minutes at the end of the half, as Mohamadou Kante skinned Regan Poole and crossed for Valentin Castellanos to guide the ball home.

The home side assumed the lead two minutes later, as the ball was worked to Jarrod Bowen who fired beyond Nico Schmid with the aid of a deflection off Conor Shaughnessy.

The home side came out fired up after the restart and put Pompey under consistent pressure.

And it was no surprise to see that result in a third goal in the 50th minute, as Bowen was left in space and afforded time to cross from the right for the unmarked Castellanos to head home.

Pompey to their credit rallied with a Segecic effort deflected off target, but were dealt a blow when sub Thomas Waddingham was forced off through injury on the hour mark.

Mousinho made a triple change at that point, sending on big Serb Marko Milovanovic, Odin Bailey and Eoin Kenny for Waddingham, Luke Le Roux and Zak Swanson.

Pompey kept pushing with players filling gaps as their lack of depth was exposed, but managed late efforts through Milanovic, Bailey, Kenny and Segecic.

Utlimately, however, the home side saw out the win with a bit to spare on a maiden trip to the London Stadium for the 9,000-strong travelling blue army.