The indomitable midfielder doubled City's lead with a superb curling shot from distance after Edin Džeko's opener to kill the contest in western Czech Republic.
Sergio Agüero added the third after a smart turn and shot from the edge of the area to give new coach Manuel Pellegrini a winning start.
Plzeň 0-3 City
"I think it is very important to start the Champions League winning away," Pellegrini said.
"It was not an easy match, against a very good team. Winning 3-0, of course we are very happy. It will give confidence for all the players."
City next face neighbours United on Sunday in the first derby of the season, which offers the Blues a chance to address their ambivalent Premier League start.
"We have the derby next Sunday and always winning away in the Champions League, scoring three goals, having at least three or four more chances to score and a clean sheet - I think it will give all the players a lot of confidence for the next games."