Zengö Motorsport BMW driver Michelisz pocketed a maximum 23 points with two victories, a pole position and two fastest laps in Sonoma.
Rival Pepe Oriola has scored only three points over the last four races and now stands 25 points behind the leader.
With 89 points yet to be awarded in the final three events of the season - race wins in Macau will be worth double - Oriola and his Tuenti Racing Team SEAT León are still in contention.
The fight for the third place is also interesting, with Stefano D’Aste chased by Alex MacDowall and Franz Engstler. They are six and 17 points behind respectively.