Viktor Gyokeres' stoppage-time penalty halted West Brom's five-match winning run as the Baggies lost 1-0 at Coventry.
The run, that included four clean sheets, had taken Carlos Coberan's men from the foot of the Championship to within touching distance of the top half.
But in a game destined for a goalless draw despite numerous chances for either side, Gyokeres twisted and turned his way into the box and was brought down by Erik Pieters.
Coventry's top scorer dusted himself down to step up and send Alex Palmer the wrong way, securing the Sky Blues' first victory since the international break.