Teenager Josh Ayala scored twice on his full professional debut as West Ham came from behind to thrash Championship rivals Southampton 4-1 in the Carabao Cup.
Nuno Espirito Santo made it clear a cup run was not his priority by fielding a team made up of four teenagers and three 20-year-olds among eight changes from Saturday's home defeat by Charlton.
Southampton took just 10 minutes to open the scoring. Tom Fellows' looping right-wing cross was cleared only to Leo Scienza on the edge of the penalty and he showed great composure to keep the ball under pressure before calmly slotting into the far bottom corner.
Saints goalkeeper Daniel Peretz then made an excellent one-handed save to keep out Joel Piroe's close-range effort in the 21st minute.
West Ham equalised against the run of play four minutes before half-time when Peretz flapped at Lewis Orford's corner and 19-year-old Ayala headed home.
The Hammers took the lead eight minutes into the second half when Ayala cashed in on Jack Stephens' poor defending to fire past Peretz from eight yards.
Taty Castellanos swept in Joel Veltman's low cross 15 minutes from time before Jarrod Bowen grabbed an 84th minute fourth to condemn Southampton to a first home defeat since January 17.
Southampton's Tonda Eckert:
"It was a very good first half and a very poor second from us.
"We had chances to go 2-0 up, conceded from a corner and from there we never found a way back into the game.
"There were some positives but as a team we need to grow and become better in a lot of different aspects."
West Ham's Nuno Espirito Santo:
"I am very proud of my young players and the character and belief they showed.
"It is important for Josh. He works hard every day in training to get chances in games. We are delighted he took the opportunity.
"We did not start very well but with these young lads we have to give them time and understand the process of their development.
"Winning breeds confidence and it is important now we build momentum from this and keep going."
