London - Manchester City cruised into the League Cup quarter-finals as Sergio Aguero's double added to struggling Southampton's misery in a 3-1 win on Tuesday.
Pep Guardiola's League Cup holders were two up by half-time at the Etihad Stadium thanks to goals from Nicolas Otamendi and Aguero.
Guardiola had made nine changes to the team that beat Aston Villa in the Premier League on Saturday, giving a debut to 18-year-old midfielder Tommy Doyle.
Doyle's grandfather Mike was City's captain when they won the League Cup in 1976 and the club remain on course to win the tournament for a seventh time.
City, who have lifted the trophy three times in the last four seasons, began the fourth round tie serenaded by chants of "We want 10" in reference to Southampton's 9-0 thrashing by Leicester on Friday.
Although City were never likely to match that incredible result, their progress to the last eight was inevitable after a one-sided first half.
The breakthrough came in the 20th minute when Bernardo Silva looped in a cross and Otamendi headed home.
City's second arrived in the 38th minute when Kyle Walker sent over a cross and Aguero, on his 350th club appearance, produced a precise close-range finish for his 11th goal of the season.
Southampton are languishing in the Premier League relegation zone amid speculation boss Ralph Hasenhuttl is in danger of being sacked.
Hasenhuttl's cause was hardly helped when Aguero made it three for City in the 56th minute, the Argentine poking in after Riyad Mahrez's shot deflected high into the penalty area.
It was little consolation for Southampton when Jack Stephens headed in from a James Ward-Prowse corner in the 75th minute.
As if the last few days haven't been painful enough for Southampton, they have to do it all again on Saturday when they return to Manchester to face City in the Premier League.
The only frustration for City was a late injury to reserve left-back Angelino.
Everton eased the pressure on beleaguered boss Marco Silva with a 2-0 win over his former club Watford.
Silva's team are just outside the Premier League relegation zone after Saturday's last-gasp defeat at Brighton.
Another loss to a Watford team with an even worse record this season could have been fatal for Silva, but Mason Holgate and Richarlison gave him some breathing space.
Everton, who have never won the League Cup, had to wait until the 72nd minute before they finally took the lead.
Theo Walcott guided the ball towards Holgate and the defender was free to thump in a header from two yards out.
Former Watford striker Richarlison completed the much-needed win with a clinical finish in stoppage-time.
Leicester joined City and Everton in the last eight with a 3-1 victory at League One side Burton.
Brendan Rodgers' team equalised the biggest margin of victory in the Premier League era when they crushed Southampton last week.
Sitting third in the Premier League, Leicester maintained their impressive form despite nine changes.
Kelechi Iheanacho got the first goal in the seventh minute when he slotted home from Youri Tielemans' pass.
Leicester, who last won the League Cup in 2000, doubled their lead after 20 minutes through Tielemans.
Liam Boyce got one back for last season's League Cup semi-finalist seven minutes after half-time, but James Maddison sealed the win in the 89th minute.
Oxford beat fellow third tier side Sunderland 4-2 on penalties after a 1-1 draw.
The 1986 League Cup winners are into the last eight for the first time since 1988 having already thrashed West Ham in the last round.
Colchester won 3-1 at fourth tier rivals Crawley as they followed up their memorable shock win over Tottenham in the previous round.