A 4-0 victory over Lazio in November 2003 had represented the Blues' last win on Italian soil in Europe's elite club competition, but this was similarly routine following a contentious Fikayo Tomori red card.

Jorginho's penalty gave the visitor a 21st-minute lead after former Chelsea defender Tomori was dismissed for fouling Mason Mount in the box.

Pierre-Emerick Aubameyang then doubled the lead before half-time, with that enough to send Graham Potter's side to the pool summit following Salzburg's 1-1 draw with Dinamo Zagreb.

Milan was reduced to 10 men in the 18th minute when Tomori was controversially shown a straight red after tangling with Mount in the box when the Chelsea man was through on goal. Jorginho then calmly sent Ciprian Tatarusanu the wrong way from the penalty spot.

Olivier Giroud, another former Chelsea player, squandered a glorious opportunity to equalise for Milan in the 27th minute, heading Brahim Diaz's inviting cross wide from eight yards out.

And the Rossoneri were to rue their wastefulness as Chelsea doubled their lead seven minutes later. As he had in a 3-0 win at Stamford Bridge six days earlier, Aubameyang netted the second with a clinical finish from Mount's neat lay-off.

Substitute Conor Gallagher went close to adding a third within four minutes of the restart but could only find the side-netting, while Aubameyang drew smart reflexes from Tatarusanu.

As Sergino Dest fired over at the other end and the Rossoneri fell to a fifth home defeat in six Champions League games against English opposition, the only dampener for Chelsea was an injury to England right-back Reece James.