CARLOS Tevez celebrated his 27th birthday in style by firing a first-half hat-trick that sentenced Albion to a seventh league defeat in nine games.
The City skipper finished a fabulous move for his second goal on 22, which was sandwiched by two penalties in the 17th and 39th minutes which the Baggies gifted the hosts.
Albion found it difficult to cope with some sparkling football from moneybags Manchester, who also twice hit the woodwork before the break.
But the three-goal margin was slightly flattering, with Joe Hart called on to deny Chris Brunt and Jonas Olsson with the game goalless.
Tevez could have added to his treble in a second half where Roberto Di Matteo's men restored some pride - and only Hart's heroics in the hosts' goal prevented them troubling the scorersheet.
Marc-Antoine Fortuné was handed his first start in nine games as Di Matteo made four changes.
James Morrison returned from his midweek rest to bolster the midfield while Simon Cox and Carlos Vela dropped to the bench.
In defence, Steven Reid and Nicky Shorey were recalled in the full-back positions, with Gonzalo Jara relegated to substitute and Marek Cech missing out with a groin injury.
Albion made a bright start but it was the hosts who came within a whisker of taking the lead in the fourth minute.
David Silva controlled Hart's punt forward and found Aleksandar Kolarov on the left and his instant cross was side-footed onto the left-hand post by Tevez from close range.
Four minutes later, Gareth Barry fizzed a ball across the six-yard box and just inches out of Tevez's reach.
The Baggies were struggling to get to grips with City's movement - and seconds later the recalled Reid had to be alert to clear for a corner and deny Yaya Toure a simple chance from Silva's chip over the visitors' backline.
At the other end, Kolo Toure's sloppy back pass almost left Hart stranded - but the Blues keeper recovered to prevent the ball rolling into his own net.
Brunt's 12th-minute free-kick proved too hot for the England shot-stopper to handle and he could only parry low down to his right and turn it around for a corner.
From the resulting Brunt flag-kick, Olsson's looping header was tipped over by Hart at full stretch.
But on 17, the Baggies switched off from a quickly-taken City free-kick and Reid brought down Kolarov for a penalty that Tevez coolly tucked away.
Five minutes later, Tevez played a delightful one-two with Silva before hurdling Olsson's challenge and slotting home to double the hosts' lead.
On the half-hour mark, Silva played a one-two with Yaya Toure but was denied a shooting chance by Olsson's flying tackle.
Seconds later, Boaz Myhill had to be at his best to finger-tip Kolarov's fierce long-range drive onto the crossbar and over for a corner.
Kolarov slid in Silva, who looked offside, in the 35th minute. But no flag was raised and the Spain international forced Myhill to save with his feet.
It was only a temporary reprieve as Jerome Thomas, who had Jerome Boateng lurking behind him, inexplicably handled a left-wing cross in his own box, giving referee Martin Atkinson no choice but to award a spot-kick.
Tevez stepped up to convert and complete a first-half hat-trick.
A rare foray by the Baggies saw Morrison's sweetly-struck 20-yard volley well saved by Hart as he dived to his right in the 40th minute.
But more pressure by Roberto Mancini's men three minutes later saw Tevez weave his way through the Baggies defence before clipping a low shot inches wide of the far post.
Di Matteo made a change at the break with new loan signing Vela coming on for Thomas.
And it was the Baggies who threatened first in the second half as Peter Odemwingie flashed a dipping 20-yard shot just past the right-hand post, with Hart beaten.
Fortuné should have given the visitors a lifeline in the 62nd minute as he latched onto Mulumbu's slide-rule pass - but he fired into the side-netting with only Hart to beat.
And Albion's luck just seemed to be out as Brunt's skidding 30-yard strike flew a yard wide of the right-hand post.
Jara came on for Brunt in the 70th minute, with Olsson getting the captain's armband.
Moments later, Hart did well to dive to his left and claw away Shorey's free-kick.
The lively Vela, who popped up all over the pitch, stole in on Morrison's right-wing cross on 74 but could not direct his header on target.
Tevez should have added a fourth in the 79th minute but lofted Barry's pull-back well over the bar, with the goal at his mercy.
The final ten minutes belonged to City as substitute Edin Dzeko three times saw shots blocked or saved by Myhill.
Right at the death, the Baggies keeper had to fling himself to his left to turn around sub Shaun Wright-Phillips' 15-yard strike to round off a goalless second half.
MAN CITY (4-5-1): Hart; Boateng, K Toure, Kompany, Zabaleta; D Silva (Rasak 90+1), Milner, Y Toure (Dzeko 63), Barry, Milner; Tevez (Wright-Phillips 86). Subs not used: Given (gk), Lescott, Vieira, J Silva.
ALBION (4-3-3): Myhill; Reid, Scharner, Olsson, Shorey; Morrison, Mulumbu, Brunt (Jara 70); Fortuné, Odemwingie (Tchoyi 88), Thomas (Vela HT). Subs not used: Carson (gk), Ibanez, Tamas, Cox.
GOALS: CITY - Tevez (pens 17 & 39, 22).
BOOKINGS: CITY - Zabaleta (foul 45). ALBION - Morrison (foul 21), Reid (foul 79).
REFEREE: M Atkinson (West Yorkshire).
ALBION STARMAN: Boaz Myhill.
PIC: HIGH JUMP...hat-trick hero Tevez hurdles Olsson