Cristiano Ronaldo set up Paulo Dybala's winner in a 1-0 Juventus victory against Manchester United at Old Trafford.
Jose Mourinho bemoaned the chasm between his Manchester United side and Juventus as the Italian champions won 1-0 on Cristiano Ronaldo's return to Old Trafford in the Champions League on Tuesday; a return muted by rape accusations against Ronaldo which he strongly denies.
Ronaldo did not get on the scoresheet, but played a supporting role by helping set up Paulo Dybala's winner on 17 minutes as Juventus opened up a five-point lead over United at the top of Group H.
Only a series of excellent saves from David de Gea prevented the margin of defeat being far greater for the hosts as any momentum United gained from fightbacks against Newcastle and Chelsea in recent weeks in the Premier League faded away against one of the favourites to win the Champions League.
Jose Mourinho's men were handed a break before kick-off as Valencia's 1-1 draw away to Young Boys means United still hold a two-point lead over the Spaniards, but a fourth defeat of the season will see speculation over Mourinho's future increase once more.
And in keeping with his complaints all season, Mourinho suggested United need to invest more in the transfer market to get to Juventus' level.
Juventus spent $129 million (112 million euros) for a 33-year-old Ronaldo in July and also brought Leonardo Bonucci back just a year after selling the Italian international to AC Milan.
"Mr Bonucci, Mr (Giorgio) Chiellini, they could go to Harvard to give some classes about how to be a central defender," said Mourinho, whose attempts to add a centre-back in the summer were thwarted.
"Juventus is champion for seven years in a row, two Champions League finals in the last four or five years and they are not happy with what they have, they want more. They had (Gonzalo) Higuain, (Mario) Manduzkic and Dybala, but they want more, they want Ronaldo," he added.
"They go for the best players in the world. A big club with a big past but also a big desire to have a big future.
Return amid rape accusations
Ronaldo was given a hero's welcome on his previous visit to Old Trafford with Real Madrid in 2013 after scoring 118 goals for United in six seasons between 2003 and 2009 to help the Red Devils win three Premier League titles and the first of his five Champions Leagues.
The Portuguese's early days as a Juventus player since making the move to Italy from Madrid this summer have been overshadowed by a rape allegation made against him in the United States, which he strongly denies.
American Kathryn Mayorga accused Ronaldo of sexually assaulting her in a hotel in Las Vegas in 2009, something the Portuguese has strenuously refuted.
German publication Der Spiegel first reported the claims, which also included the suggestion Ronaldo paid Mayorga $375,000 in 2010 as part of a privacy agreement, preventing her from going public with the allegations.
Ms Mayorga filed a lawsuit in an attempt to quash that agreement while Las Vegas police have re-opened an investigation.
Ronaldo's lawyer Peter Christiansen confirmed the payment was made to Mayorga, but said some documents presented as evidence had been "stolen" and "completely fabricated".
And the reception Ronaldo received from the United faithful this time was far more muted, although he was applauded off the field at the end of the game after taking a selfie with a pitch invader, who was hauled away by security staff.