Manuel Pellegrini's team made it seven wins from as many Premier League matches at the Etihad Stadium against Swansea on Sunday but they arrived at the Hawthorns with one win and four defeats in six attempts outside Manchester.
Sergio Aguero's 17th goal in as many starts this term and Yaya Toure's eighth of the season made light of those struggles and City should have had more than those two wonderfully crafted team efforts to show for a dominant opening 45 minutes.
Toure sealed the victory with a 73rd-minute penalty before West Brom rallied late on through Costel Pantilimon's own goal and Victor Anichebe's injury-time strike, but City retained their position in third on a night when the Premier League's top five were all victorious.
Edin Dzeko, scorer of all three City goals in two wins over West Brom last season, was recalled and found himself instantly involved - chesting down Toure's pass for Aguero to fire wastefully wide.
Aguero soon atoned for his error, emphatically converting Pablo Zabaleta's cutback to cap a superb ninth-minute team move.
Steve Clarke's men displayed renewed purpose throughout the second period and, after Claudio Yacob had clipped Kolarov in the area for Toure to convert, they mounted a belated comeback.
Substitute Matej Vydra got to the byline and Kolarov's miscued clearance struck his own, prone goalkeeper Pantilimon and nestled in the net.
