West Ham United produced a devastating seven-minute spell to come from behind and beat Portsmouth 3-1 in the first round of the Carabao Cup at the London Stadium.
Portsmouth took a deserved lead after 30 minutes when Adrian Segecic's effort from outside the penalty area deflected off Max Kilman and flew beyond goalkeeper Mads Hermansen.
The visitors had enjoyed much of the possession during the opening half, with new signing Rocco Shein particularly impressive in midfield.
Shein almost doubled Portsmouth's advantage shortly before the interval, forcing Hermansen into a diving save with a powerful long-range strike.
But West Ham responded immediately.
Mohamadou Kante delivered a low cross into the area and Valentín Castellanos converted to bring Nuno Espirito Santo's side level.
Just two minutes later, Jarrod Bowen completed the turnaround.
The West Ham captain's left-footed effort from outside the box took a deflection off Conor Shaughnessy, wrong-footing goalkeeper Nicolas Schmid before finding the net.
The Hammers carried their momentum into the second half and quickly extended their advantage.
Bowen raced into space on the right before delivering a perfectly weighted cross for Castellanos, who headed into the bottom corner for his second goal of the game.
It completed a remarkable spell in which West Ham scored three times in just seven minutes, transforming a difficult evening into a commanding lead.
The hosts had initially struggled to create opportunities, with Edson Alvarez heading their best early chance harmlessly towards Schmid from a corner.
Former West Ham co-chairman David Sullivan was also in attendance despite previously being advised to stay away from home matches at the London Stadium.
Portsmouth offered little attacking threat after falling two goals behind, allowing West Ham to comfortably manage the closing stages and secure their place in the next round of the Carabao Cup.
