Jose Mourinho???s men went six points clear before this game kicked off with a win 2-0 over West Ham but City responded in emphatic style.
They had the game sewn up by half-time with three goals in the opening 34 minutes.
A Ben Foster mistake handed Fernando a late Christmas present with just four minutes gone before Yaya Toure doubled the lead from the penalty spot on 13 minutes.??
West Brom had their chances but David Silva’s 34th minute goal gave City a lead that the hosts couldn’t overturn.??
Brown??Ideye netted a scrappy late goal but it was nothing more than a consolation for the hosts.??
West Brom came into this game with just one win from their last 13 matches and their nerves were clear from the start as City took the lead inside four minutes.
Christmas may have passed but West Brom???s goalkeeper Ben Foster still was giving out gifts by spilling a routine cross right under the nose of Fernando six yards from goal.
The City midfielder needed no second invitation and cleverly hooked the ball into the unguarded net.
Things went from bad to worse for the hosts in front of a restless home crowd when Joleon Lescott, who endured a nightmare game against his former club, fouled Silva as he jinked his way into the penalty area.
From the spot, Toure confidently stroked the penalty into the corner of Foster???s net.
Despite being two goals down with just 14 minutes on the clock, West Brom responded well and Saido Berahino went close to reducing the deficit two minutes later but fired wide after being played through by James Morrison.
Silva made the West Brom forward pay for that miss on 34 minutes when he got the goal his performance merited.
Lescott squandered possession to Fernando on the half-way line and City broke at lightning speed.
Jesus Navas, under no pressure from a West Brom defender, drove his way into the area before squaring the ball to Silva, who had all the time in the world to cleverly pick out the far corner with a precise finish.
The only thing that looked likely to threaten a City victory was the snowstorm that engulfed The Hawthorns in the second half. As soon as the whistle was blown to start the half the snow began to fall and didn???t relent for the remainder.
Conditions became tricky as the snow began to settle and the game suffered in quality as a consequence but referee Mike Clattenburg never looked like considering an abandonment to the dismay of the home crowd who were chanting ???let it snow.???
West Brom had the better of the play in the conditions but some wayward finishing by Sessegnon and a missed header from three yards out from Lescott failed to give West Brom a base to launch a comeback.
Ideye did find the net late on for the hosts – his first goal for the club since his ??10m move from Dynamo Kyiv – but it was hardly one to remember as Joe Hart flapped at a cross and the ball bounced off the back of the forward???s head and into the net.