After an eventful start – during which Sadio Mane felt that he should have been awarded a penalty when his bicycle kick struck the hand of Andreas Christensen – the French veteran handed Chelsea the advantage.
He owed much to new signing Christian Pulisic, who enjoyed an electric opening half.
Picking up the ball in midfield, the United States international drove forward, escaping the attentions of Fabinho.
Rather than shoot, Pulisic then slipped the ball across the face of goal, where Giroud was waiting.
How well does Christian Pulisic do here?!
Olivier Giroud scores in Europe again after being set-up perfectly by the new signing 👏 pic.twitter.com/d2XKYKAjSV
— Football on BT Sport (@btsportfootball)
The Frenchman elected to shoot first time – angling his shot across the face of goal and beating Liverpool’s back-up goalkeeper Adrian.
The goal was enough to see Chelsea head into the break with a 1-0 lead.