Titleholders Bayern Munich, Real Madrid and Paris Saint Germain emerged from the second batch of Champions League action with comfortable wins on Wednesday while the two clubs from Manchester endured differing fates.
David Moyes' United, after their worst start to a domestic campaign in 24 years, were held to a dour 1-1 draw by Shakhtar Donetsk in a game that went ahead without injured Wayne Rooney.
The stalemate, after Danny Welbeck's early opener was cancelled out by Taison 14 minutes from time, left United level pegging with Shakhtar at the top of Group A, after Bayer Leverkusen beat Real Sociedad 2-1.
United's veteran Welsh international Ryan Giggs came on in the second half to overtake Raul with at 145 the most appearances in Europe's top club competition.
Humbled at home
Back in Manchester, at the Etihad stadium, City were humbled 3-1 by brilliant Bayern, playing in England for the first time since claiming the trophy at Wembley last season, in a clash that reunited City's manager Manuel Pellegrini with Pep Guardiola.
The pair are old foes from Spain, when they occupied the dugouts at Real Madrid and Barcelona respectively in 2009-10.
Guardiola it was who came away with the bragging rights this time after goals from Franck Ribery, Thomas Mueller and Arjen Robben - Alvaro Negredo getting a late consolation for City - pushed the German giants onto six points and firmly in command of Group D.
City lie second on three points with CSKA Moscow, 3-2 winners over Viktoria Plzen, in third on goal difference.
Pellegrini's predecessor at City, Roberto Mancini, enjoyed a baptism of fire in his first game just 48 hours after being appointed coach of Galatasaray.
Didier Drogba gave Mancini the perfect start, putting the Italian's new Turkish club into the lead - but Juventus hit back with a late double from Arturo Vidal's penalty and Fabio Quagliarella before substitute Umut Bulut's bagged the equaliser two minutes from time.
Galatasaray, who are bottom of Group B, had been hammered 6-1 by table toppers Real Madrid last time out and Real were at it again, drubbing FC Copenhagen 4-0 at the Bernabeu with doubles from Cristiano Ronaldo and Angel di Maria.
The nine-time European kings are well on course for the last 16, four points ahead of Juve with the Italians next up to visit Real's stronghold.
At the Parc des Princes PSG were sitting pretty on six points and occupying the Group C summit after their 3-0 win over shell-shocked Benfica.
The moneyed Parisians indicated that they are genuine title contenders with a stunning first-half display thanks to superbly-worked goals scored by Zlatan Ibrahimovic and Marquinhos and another effort by the Swede.
Benfica tread water on three points, ahead only on goal difference from Olympiakos who defeated Anderlecht by an identical scoreline.