The Bianconeri was ahead after just three minutes when Aaron Ramsey nudged the ball over the line after goalkeeper Guilherme had spilled Cristiano Ronaldo's free-kick back towards his goal.

However, Lokomotiv soon hit back through Aleksey Miranchuk and Guilherme denied Ronaldo twice in the second half as the Portuguese attempted to set a Champions League record by scoring against a 34th different team.

It was not to be Ronaldo's night as he was replaced with nine minutes to go, yet Costa stepped up to be the hero, weaving in off the left wing and finishing after a one-two with Gonzalo Higuain.