City started the match on a slow even though Sergio Aguero came close but was denied by the post. However, City's skipper Kompany produced the game's decisive moment after the break with a breathtaking 30-yard strike.
He was meant to have been phased out long ago. He wasn't Pep Guardiola's type, remember. He wanted defenders like midfield players, not old fashioned warrior centre-halves. Plus, there were the injuries. In Guardiola's first season here. Kompany's struggles were so bad the manager didn't even include him in his thinking. If he was available, if he could play, it was a bonus.
Yet here he is, three years into Guardiola's revolution, scoring the goal that leaves Manchester City on course for the most competitively fought title in history.
The result puts Pep Guardiola's side a point ahead of second-placed Liverpool with just one league match left. City's final match will be against Brighton while Liverpool will host Wolves.
If they win, City would also become the first club to secure back-to-back Premier League titles since rivals Manchester United in 2007-08 and 2008-09.
Ninety eight points. That is what they will need, in all likelihood, to win it. They would have fallen short without Kompany and a goal that will be remembered, replayed and celebrated decades from now. A spectacular goal, not the type traditionally scored by players in his position. This was his Aguerooo moment.