Willian, Gary Cahill, Eden Hazard and substitute Bertrand Traore scored second-half goals to extend Guus Hiddink’s 100 per cent record in the competition to six games.
The forward, on loan from Turkish side Fenerbahce, twice nearly had a hat-trick on his first West Ham start, a shot coming back off the post before another effort was ruled out for offside in stoppage time.
West Ham manager Slaven Bilic compared Dimitri Payet to Real Madrid star Luka Modric after the playmaker inspired a five-goal drubbing of Blackburn to send the Hammers into the FA Cup quarter-finals on Sunday.
Rovers, who played the last 35 minutes with 10 men after Chris Taylor’s sending-off, had led through free-scoring right-back Ben Marshall but never looked like threatening a shock like the one a year ago when they dumped out Premier League Stoke 4-1.
West Ham United’s Dimitri Payet, foreground, scores the second goal…
“I have 13 players (fit), I can not take the risk to have one player more injured” Pellegrini said, when asked if he had devalued the FA Cup by fielding a weakened team.
The Scot’s side are eight points above the drop zone, a comfortable cushion, yet Lambert still chose to make five changes, to Bilic’s four – resting Corry Evans, Grant Hanley and Jordi Gómez, who would usually make the strongest XI here.
Not for the first time this season, Payet was not always constantly involved in the game – but it is his ability to burst into life with devastating effect which is so impressive.
A full-strength Chelsea could even afford the luxury of a missed penalty when Oscar’s kick was saved by City’s second-choice keeper Willy Caballero.
“When we went up a goal they would have felt a bit edgy, and that was the intent, to get them on edge”, said the Rovers chief.
The Hammers boss told the BBC’s Match of the Day: “We played some fantastic football“.
Understandably Emenike’s performance went down very well with most West Ham fans.
Monday sees Manchester United looking to ease the pressure on under-fire manager Louis van Gaal following their 2-1 Europa League defeat by Danish side FC when Midtjylland when they travel to third-tier Shrewsbury.
West Ham swept Blackburn aside to stroll into the quarter-finals and Bilic says they are desperate to keep progressing.