Manchester United face a reunion with Cristiano Ronaldo after being pitted against Juventus in the Champions League group stage.

Tottenham and Liverpool received tough draws as top-seed Manchester City got a favourable group, but the return of an Old Trafford favourite at a difficult time was arguably most eye-catching.

Back-to-back defeats have ratcheted up the pressure on United manager Jose Mourinho, who may not get much respite in a Champions League group that also includes Valencia and Young Boys.

Finalists in two of the previous four years, the Serie A champions are Group H favourites and have been bolstered by the summer arrival of United favourite Ronaldo.

The Portuguese became a global star during his time at Old Trafford and Mourinho knows better than most about his compatriot's threat after working together – sometimes uneasily – at Real Madrid.

Cross-town rivals City benefitted from their place in pot one of Thursday's draw at the Grimaldi Forum in Monaco.

Pep Guardiola's Premier League champions face Shakhtar Donetsk again, with Lyon and Hoffenheim completing Group F.

Liverpool and Tottenham, on the other hand, face far tougher asks.

Barcelona, Inter Milan and PSV Eindhoven are the Group B opponents for Mauricio Pochettino's Spurs, who also have to deal with off-field complications brought by their stadium delay.

Tottenham have agreed with UEFA that their first home Champions League group match will be held at Wembley, but it is unclear what happens after that.

Giorgio Marchetti, UEFA's deputy secretary general, said of the stadium issue: "In principle the regulations state that you have to play in a single stadium, but we will have to see."

Last season's runners-up Liverpool also face difficult group-stage assignments.

The Reds were in pot three despite their 2017-18 heroics and will face Paris Saint-Germain, Napoli and Red Star Belgrade in Group C.

"To be 100 per cent honest, it was not that I had a group I wished for or whatever," Liverpool boss Jurgen Klopp told the club's official website.

"I expected a difficult group, we have a difficult group and that's what the Champions League is all about.

"PSG are one of the most exciting teams in the world and I think their target is to win the Champions League, so that will be two interesting matches.

"Napoli, we beat them in pre-season but it goes without saying these two games will be completely a different challenge."

Klopp is expecting "a very, very intense atmosphere" at Red Star, who confirmed earlier in the day that UEFA had accepted their appeal against an impending stadium ban for racist chanting.

The UEFA Control, Ethics and Disciplinary body announced earlier this month that the Serbian champions would have to play two matches behind closed doors, with a one-match ban for racist behaviour against FK Suduva in July kicking a suspended disciplinary measure into force.

Red Star were also fined 72,000 euros (£64,500) but a statement on the club website confirmed that the second match of the ban has now been wiped off.

"Two-match stadium ban has been changed to one-match stadium ban and a fine," the group-stage debutants said.

"The stadium ban has already been served since we played our Champions League play-off first leg match against FC Salzburg in front of empty stands.

"Football is nothing without fans and we are delighted to have our supporters with us when we play in the UEFA Champions League."

Elsewhere, Europa League holders Atletico Madrid's bid to reach the final held at their Wanda Metropolitano home starts in Group A against Borussia Dortmund, Monaco and Club Brugge.

Bayern Munich, Benfica, Ajax and AEK Athens make up Group E, with holders Real Madrid joined by Roma, CSKA Moscow and Viktoria Plzen in Group G.

Group D looks the easiest of the eight, with Lokomotiv Moscow, Porto, Schalke and Galatasaray drawn together.