Alvaro Negredo claimed a hat-trick as Manchester City demolished struggling West Ham 6-0 in the first leg of their Capital One Cup semi-final.
Edin Dzeko grabbed two and Yaya Toure also got on the scoresheet as City all but booked a trip to Wembley by piling on the misery for the Hammers and their under-fire manager Sam Allardyce.
City needed just 12 minutes to take the lead at the Etihad Stadium and the Londoners were simply swept aside in an embarrassingly one-sided match.
Allardyce, who was taunted by visiting fans late in the game, had prioritised the game to some extent by fielding a weakened side against Nottingham Forest in the FA Cup third round last weekend.
But that backfired as they were thrashed by six goals and despite eight changes, including the return of senior players such as Mark Noble, Joe Cole, Guy Demel and Mohamed Diame, it proved a similar story in the Manchester rain.
It was also a particularly chastening debut for Roger Johnson, who looked well off the pace after arriving on loan from Wolves to bolster the defence this week.
With cup football now effectively over, this weekend's trip to Cardiff in the Barclays Premier League is taking on crucial importance for Allardyce.
For City, it was another irresistible display to add to a growing catalogue that has already seen them put six past Arsenal and Tottenham and score seven against Norwich this season.
They might even have had more but for a number of good saves from Hammers goalkeeper Adrian.
Summer signing Negredo's treble took his tally for the season to 18, one behind injured team-mate Sergio Aguero.
The hosts certainly needed little time to break into their stride as they took immediate command of the game.
West Ham were troubled in the opening moments as Samir Nasri cut open their defence and Toure crossed looking for Pablo Zabaleta.
The Argentinian was denied a shot but the ball rebounded and Adrian needed to keep out a ricochet off Negredo.
The warning signs were clearly there as Javi Garcia headed narrowly wide from a corner.
City took the lead as Toure, with plenty of time in the centre of the field, picked out Negredo with superb long ball.
The Spaniard's technique was equally brilliant as he allowed the ball to drop over his shoulder before lashing a powerful left-foot volley into the bottom corner.
After that it seemed all too easy for City as Toure robbed Mohamed Diame to launch a raid that led to David Silva and Nasri testing Adrian from long range in quick succession.
As the attack went on Toure stayed down having been hurt in the challenge and there were concerns as he was helped from the field, but City's talismanic midfielder soon returned.
City doubled their lead after 26 minutes as Negredo latched onto a fine ball from strike partner Dzeko and confidently drove across Adrian into the top corner.
City continued to bombard the beleaguered visitors as Dzeko twice fired over and Negredo also missed the target.
Toure, having clearly run off his knock, then charged through the back-tracking Hammers defence with alarming ease to poke home City's third five minutes before the interval.
Allardyce sent on Carlton Cole for the second half in an attempt to give his side more shape and firepower but it made little difference.
Negredo completed his hat-trick within four minutes of the restart as he curled a shot past Adrian after Dzeko and Silva had combined.
Toure then fired over from a free-kick and Dzeko sent a long-range effort narrowly over the bar.
There was no respite for the visitors and Silva cut them open again with a cross-field pass for Gael Clichy and the Frenchman's cross was slid home by Dzeko for 5-0 on the hour.
That marked the end of Toure's work for the night as Pellegrini started to look ahead to weekend trip to Newcastle.
Yet Pellegrini's attacking ethos did not change and Johnson recovered to block a Negredo shot and Adrian beat away a Dzeko header.
Adrian produced another good stop to deny Dzeko after another incisive move but it merely stemmed the tide as the Bosnian thumped in City's sixth from an Aleksandar Kolarov cut-back a minute from time.
5 minutes - Javi Garcia heads wide from David Silva's corner
12 - Alvaro Negredo puts City 1-0 up, producing a delightful first-time left foot finish as he connects with Yaya Toure's long ball from the City half.
18 - Mohamed Diame picks up possession and drives forward, but can only drill the ball wide from outside the box.
22 - Adrian pushes away a Silva strike as City step up the pressure.
23 - The West Ham goalkeeper parries again within seconds, this time doing well to dive and tip Samir Nasri's shot behind.
26 - City cut through West Ham once more as Negredo latches on to Edin Dzeko's through-ball and makes it 2-0 by firing into the net.
34 - Negredo, looking for his hat-trick, shoots off-target from outside the area.
35 - Matthew Taylor tries to threaten Costel Pantilimon's goal, but misses by some distance as he strikes into the stand.
36 - Dzeko scoops the ball over from a good position in the box.
40 -Toure is allowed to run unchallenged through to the West Ham box and crack in City's third.
49 - The ball deflects from Silva to Negredo, who completes his hat-trick, curling into the corner.
52 - Toure sends a free-kick whistling just over the bar.
54 - Dzeko arrows the ball inches too high.
55 - Dzeko tumbles in the Hammers area when challenged by Joey O'Brien, no penalty is given and there is a brief skirmish between the two players.
60 - Dzeko gets a deserved goal, sliding in to convert Gael Clichy's cross.
70 - Adrian gets down on his line to keep out Dzeko's header.
82 - Dzeko's drive is turned behind by Adrian.
89 - Dzeko lashes in City's sixth from Aleksandar Kolarov's cut-back.
DZEKO LOSES COUNT AFTER ROUT
Such was Manchester City's dominance of their Capital One Cup semi-final first leg against West Ham that even Edin Dzeko lost track of the score.
Dzeko scored the final two goals in City's 6-0 rout, adding to Alvaro Negredo's hat-trick - the first a beautifully-taken left-foot volley - and Yaya Toure's solo goal.
And the towering Bosnian told Sky Sports 1: "It's not easy to win 5-0 at home against another Premier League team.
"We still have to play away and this 5-0 - or 6-0, in the end - will give us the confidence for the second leg.
"The first goal is always important, then maybe we can open them up because they were defending with eight, nine players always.
"The first goal was also spectacular from Alvaro."
Negredo played down his personal contribution and said through an interpreter: "I'm very happy, obviously, but especially about the team. We got the victory so that's what matters in the end."
On his partnership with Dzeko, the Spain international added: "People were able to see today, when we play together we feel comfortable. We try to find each other and we got the results tonight."
Manager Manuel Pellegrini was delighted to as good as clinch a place in next month's final at Wembley.
"Today was an important result to play at Wembley," he said. "In football it is never finished until the end but today we have one leg in the final.
"The most important thing was not to score the six goals, it is the way the team must play.
"It is good to score goals but it is very important not to concede goals. If we keep playing this way the goals will come.
"Tonight we were a very balanced team, we didn't give up one counter-attack."
HOW SAM ALLARDYCE FARED AT THE ETIHAD
The pressure was on West Ham boss Sam Allardyce ahead of his side's Capital One Cup semi-final first leg at Manchester City.
The Hammers are currently second-bottom of the Barclays Premier League, have only one win in their last 13 top-flight games, and went into this contest on the back of a humiliating 5-0 defeat to Sky Bet Championship outfit Nottingham Forest in the third round of the FA Cup.
After fielding a hugely inexperienced side at Forest, Allardyce made eight changes to his first XI, with Adrian, Stewart Downing and Modibo Maiga the only players retained.
Roger Johnson, recruited on loan from Wolves this week, went straight into the team while the likes of Mark Noble, Joe Cole, Mohamed Diame and Guy Demel came in.
Allardyce sent his side out in a 4-3-3 formation, which seemed positive enough, but falling 2-0 behind within the first 26 minutes would not have been part of the plan. The visitors were pinned back in their own half increasingly as City attacked again and again.
With West Ham 3-0 down at half-time, Carlton Cole was brought on for Maiga as the second period got under way, but within four minutes City had another goal. Alou Diarra then replaced Mark Noble, and again, the hosts swiftly scored, perhaps leaving Allardyce wishing he had not bothered to try to freshen things up at all. The Hammers' final change saw Razvan Rat come on for Joey O'Brien with 15 minutes remaining.
For most of the first half Allardyce, with his hood up to shield him from the driving rain, sat looking thoroughly fed up as he chewed gum and City cut through his defence.
He shook his head after Negredo's opener, which was a fine finish from a decent delivery, but ultimately a route-one goal. And his reward for venturing into his technical area towards the end of the first half was to almost immediately see Yaya Toure being allowed to run unchallenged through to the West Ham box and score. He reacted by popping another piece of gum into his mouth.
With the one-way traffic continuing after the break, there was little to improve Allardyce's mood.
The West Ham fans did their best to roar on their team throughout the match in what were all-round miserable conditions for them, and seemed generally to be in good spirits. But hostile chants towards Allardyce started to emerge from the away section midway through the second half and continued to do so through to the final whistle.