Arsenal’s Dowman Eyes History While Real Madrid Chases Milestones.

Arsenal teenager Max Dowman is on the verge of making Champions League history. If the winger steps onto the pitch against Athletic Bilbao on Tuesday, he’ll become the youngest player ever to feature in the competition. Dowman, who already became the second-youngest Premier League player last month, is just 15 years and 259 days old.

This week also marks the return of the Champions League’s new “league phase” format. Now in its second season, the revamped structure features 36 clubs each playing eight different opponents on a weighted schedule, all feeding into a single standings table. The opening round is spread across three days.

Elsewhere, Real Madrid is chasing history of its own. The 15-time European champions host Marseille and are within touching distance of two landmarks: one more win will be their 200th in the competition, and two more goals will bring their tally to 700. History is on their side — Madrid has won all four of its previous meetings with the French club.

Other storylines across the continent add intrigue:

• Belgian champions Union Saint-Gilloise make their Champions League debut away at PSV Eindhoven.

• Azerbaijan’s Qarabag faces a long trek to Lisbon to take on Benfica.

• Tottenham begins its campaign against Villarreal.

• Juventus, boosted by in-form striker Jonathan David — seven goals in his last nine league matches — welcomes Borussia Dortmund.

Under the current format, the top eight finishers advance directly to the round of 16, while the next 16 enter a playoff round to fight for the remaining spots.