West Ham United scored three goals in seven minutes as they came from behind to beat Portsmouth in the first round of the Carabao Cup at the London Stadium.

Pompey broke the deadlock when Adrian Segecic's deflected strike flew into the left-hand side of the hosts' net.

But the Hammers turned the match on its head just before the interval as Valentín Castellanos and Jarrod Bowen scored in the space of two minutes to put Nuno Espirito Santo's side in front.

West Ham then added to their lead as Bowen's lofted cross found Castellanos, who headed the ball home.

Former West Ham co-chairman David Sullivan was in attendance at the game despite being advised he should stay away from home matches at the London Stadium.

After a slow start to proceedings the hosts came closest to an opener as Edson Alvarez rose highest from a corner to head towards goal, but his attempt failed to trouble keeper Nicolas Schmid.

Portsmouth found an opener after 30 minutes as a half-cleared cross fell to Segecic just outside the box.

The Croatian fired a shot towards goal that went into the net via a deflection off Max Kilman, sending the 9,000 travelling fans wild in celebration.

Portsmouth had most of the possession in the first half - with new signing Rocco Shein impressing in midfield - much to the frustration of the home fans.

The visitors came close to a second just before the break as Shein let fly with a right-footed shot from distance which was dealt with by the diving Mads Hermansen.

But the Hammers dragged themselves back into the game immediately after that attempt on goal when Castellanos slotted the ball into the net from a low Mohamadou Kante cross.

Bowen then gave his side the lead in the 45th minute, his left-footed strike from outside the box deflecting off the head of Conor Shaughnessy, wrong-footing Schmid and flying into the net.

And West Ham impressively picked up from where they left off as the second half got under way.

Bowen broke into space down the right before crossing to Castellanos, who headed into the bottom left-hand corner of the net to finish off a stylish attacking move.

The Hammers held firm for the rest of the game to reach the next round, with Portsmouth providing little threat.