London, November 1: Son Heung-min returned to form in emphatic fashion as his double helped Tottenham to a 3-1 victory at West Ham to send Mauricio Pochettino's side into the EFL Cup quarter-finals.
Having opened the scoring with his first goal of the season 16 minutes in, Son, one of 10 changes and making his 150th Spurs appearance, doubled his tally with a composed finish early in the second half to set Tottenham on their way to a second victory at London Stadium in the space of 12 days.
Son's goals – his first since March – were Tottenham's only opportunities of note amid a barrage of West Ham attacks, though, and the hosts' pressure paid off when Lucas Perez headed in with 19 minutes remaining.
However, West Ham's hopes of a comeback were dashed inside four minutes, Fernando Llorente tucking home from close range to secure progress into the last eight.
Son wasted little time in opening his account for the campaign, picking out the top corner after latching onto a loose ball on the edge of the area.
West Ham rallied quickly and Tottenham had Paulo Gazzaniga to thank when he pulled off a smart stop low to his right to deny Javier Hernandez an equaliser on the stroke of half-time.
Michail Antonio looked set to restore parity shortly after the restart, but the forward failed to beat Gazzaniga after outmuscling Juan Foyth.
Manuel Pellegrini's side were soon punished for their wastefulness, Son pouncing on Arthur Masuaku's error before coolly rounding Adrian.
Perez's header threatened to make things interesting late on, but West Ham's defence was exposed again when Llorente reacted quickest to Christian Eriksen's corner to wrap up the victory.
What does it mean? Pochettino's back-ups come good
With just 48 hours between this game and their defeat to Premier League title rivals Manchester City, Pochettino had little choice but to make wholesale changes.
Fortunately for Tottenham, their strength in depth shone through as West Ham, who trounced Macclesfield Town 8-0 in the third round, failed to make their chances count.
Son off the mark in style
Son scored 14 goals in all competitions last term, but following his exploits at the World Cup and then the Asian Games, it has taken time for the South Korea forward to click into gear.
With neither Lucas Moura or Erik Lamela presenting as obvious goalscorers, Son will be hopeful his double has forced him back into starting contention.
Hernandez fails to take his chance
Having made just two Premier League starts this season, Hernandez needed to grasp his opportunity with both hands on Wednesday if he is to mount a challenge to Marko Arnautovic, but despite finding himself in good positions, the former Manchester United striker failed to take advantage.
West Ham host Burnley in their next Premier League outing, while Tottenham travel to Wolves in a late kick-off on Saturday (November 3).