Romelu Lukaku scored his fourth goal in four games as Chelsea began the defence of their Champions League trophy with a hard-fought 1-0 win at home to Zenit St Petersburg.
Thomas Tuchel made five changes to the side that beat Aston Villa, including dropping new signing Saul Niguez, and the German cut a frustrated figure on the sidelines as his team had an off night with their passing.
The Russians defended solidly and compactly, restricting the Blues to few opportunities and it took them 47 minutes to register their first shot on target.
Tuchel brought on Champions League final hero Kai Havertz for the disappointing Hakim Ziyech on the hour mark and their tempo improved.
They eventually broke the deadlock with Cesar Azpilicueta's cross headed in from close range by Romelu Lukaku, reward for the Belgian's work-rate and hold up play.
Zenit brought on Artem Dzyuba and Aleksandr Erokhin in the closing stages and the former missed a golden opportunity to equalise, toe-poking an effort wide from close range, as the home side held on.