LONDON (Reuters) -Romelu Lukaku opened his Champions League account for Chelsea as his powerful header earned the holders an unconvincing 1-0 victory over Zenit St Petersburg at Stamford Bridge in their Group H opener on Tuesday.

It had been an uncomfortable night for the defending champions against a well-organised Russian side but in the 69th minute the big-money striker Lukaku broke the deadlock with a header straight from the centre forward's handbook.