Ronaldo, who was at United between 2003 and 2009, joined Juve for £ 99.2m in July after nine years at Real Madrid.

Valencia and Young Boys are the other teams in Group H.

Tottenham have been drawn in a tough group to face Barcelona, ​​while last season's runners-up Liverpool face Paris St-Germain and Napoli.

Eredivisie champions PSV Eindhoven and Inter Milan complete the line-up in Spurs' Group B and Red Star Belgrade are the other team to play Jurgen Klopp's side in Group C.

Premier League champions Manchester City were drawn in Group F alongside Shakhtar Donetsk, Lyon and Hoffenheim.

Last season's winners Real Madrid, who have won the competition for the past three years, are in Group G with Rome, CSKA Moscow and Viktoria Plzen.

Group stage draw in full:
Group A: Atletico Madrid, Borussia Dortmund, Monaco, Club Brugge.

Group B: Barcelona, ​​Tottenham, PSV Eindhoven, Inter Milan.

Group C: Paris St-Germain, Napoli, Liverpool, Red Star Belgrade.

Group D: Lokomotiv Moscow, Porto, Schalke, Galatasaray.

Group E: Bayern Munich, Benfica, Ajax, AEK Athens.

Group F: Manchester City, Shakhtar Donetsk, Lyon, Hoffenheim.

Group G: Real Madrid, Rome, CSKA Moscow, Viktoria Plzen.

Group H: Juventus, Manchester United, Valencia, Young Boys.

When are the group stage match days?
Match day one: 18-19 September

Match day two: 2-3 October

Match day three: 23-24 October

Match day four: 6-7 November

Match day five: 27-28 November

Match day six: 11-12 December

Ronaldo v United - the stats:

Cristiano Ronaldo has scored in both of his previous Champions League appearances against Manchester United for Real Madrid in February and March 2013.

Manchester City manager Pep Guardiola faced Lyon with Barcelona in the last 16 in 2008-09 on the way to winning the first of his two Champions League titles as a manager.

Liverpool met Red Star Belgrade in the last 16 of the European Cup in 1973-74, with the Reds losing both the home and away legs.

Tottenham met Inter Milan in the 2010-11 group stage, losing 4-3 away from home (despite Gareth Bale's hat-trick) and winning 3-1 at home.