Jose Mourinho will return to the club where he started his Trophy-laden career Porto.
That's the consequence of the draw for the Champions League made this afternoon.
The Blues will also face Dynamo Kiev, Maccabi Tel-Aviv.
Full Champions League group draw
Group A: Paris St-Germain, Real Madrid, Shakhtar Donetsk, Malmo
Group B: PSV Eindhoven, Manchester United, CSKA Moscow, Wolfsburg
Group C: Benfica, Atletico Madrid, Galatasaray, Astana,
Group D: Juventus, Manchester City, Sevilla, Borussia Monchengladbach
Group E: Barcelona, Bayer Leverkusen, Roma, BATE Borisov
Group F: Bayern Munich, Arsenal, Olympiakos, Dinamo Zagreb
Group G: Chelsea, Porto, Dynamo Kiev, Maccabi Tel-Aviv
Group H: Zenit Saint Petersburg, Valencia, Lyon, Gent