Cristiano Ronaldo is going back to Manchester United and Paul Pogba will return to Juventus after the teams were drawn together in a Champions League group along with Valencia and Young Boys on Thursday.
After winning four titles at Real Madrid, and one with United, Ronaldo aims to end Juventus' 23-year wait for a third European title.
Three-time defending champion Madrid will play Roma, CSKA Moscow and Viktoria Plzen.
Barcelona heads a tough group with Tottenham, PSV Eindhoven and Inter Milan, while three former European champions Bayern Munich, Benfica, Ajax are together with AEK Athens.
Liverpool, the runner-up last season, was the toughest third-seeded team and landed with Paris Saint-Germain, Napoli, and Red Star Belgrade.
English champion Manchester City got a favorable group with Shakhtar Donetsk, Lyon and Hoffenheim.
Atletico Madrid, whose Metropolitano stadium hosts the final on June 1, is grouped with Borussia Dortmund, Monaco and Club Brugge.
Lokomotiv Moscow, seeded in the top pot, will play Porto, Schalke and Galatasaray.
The 32 teams will share a record 1.95 billion euros ($2.28 billion) in prize money from UEFA.
Games kick off on September 18.
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