Triumphant return for Cristiano Ronaldo as Juventus outclasses Manchester United at Old Trafford. Halfway through the Champions’ League group stages, all the evidence points to Juventus ending a 23-year wait to win a third European Cup come the time when the 2019 final will be staged at Atletico Madrid's Wanda Metropolitano stadium.

Juventus is one of only three teams -- along with Barcelona and Borussia Dortmund -- in this season's competition with a 100% record.

Obviously you can never discount Barcelona and Lionel Messi, while Manchester City's billion-dollar squad under Pep Guardiola, who has won the European Cup both as a player and coach, is another team that is hard to ignore.

But Barca's La Liga defense has already exposed vulnerabilities -- in nine games they've lost one, drawn three and conceded 11 goals -- while City's opening Group F defeat by Lyon signaled weaknesses in the English team's defense.

Moreover last season City exited the Champions League at the quarterfinal stage after being outfoxed by Liverpool and even Guardiola has talked about his side not being "ready" yet to win the Champions League.

Defensive weakness is a charge rarely leveled at Juventus. Marshaled by Leonardo Bonucci and Giorgio Chiellini, Juve had Manchester United in football's equivalent of a UFC choke hold as the Serie A team emerged with a third successive clean sheet in Group H on Tuesday.

"Mr. Bonucci, Mr. Chiellini, they could go to Harvard to give some classes about how to be a central defender," Manchester United manager Jose Mourinho told reporters after his side's inability to really threaten Juventus in the Serie A club's 1-0 victory at Old Trafford.

In days gone by Italian teams' strategy when they traveled abroad for European games was to frustrate their opponents with a blanket defense and hope to hit them on the counterattack.

At times Bonucci's passing was so good he was like an additional midfielder, while right back Joao Cancelo's outstanding performance saw him act more as a winger -- frequently gamboling forward like a gazelle -- than a defender given the amount of time he spent in the United half.

Yet it was Juventus' collective performance on Tuesday in their 1-0 win rather than the flashes of Cristiano Ronaldo's brilliance that are lodged in the memory bank, which speak volumes about their strength in depth -- Brazilian Douglas Costa was only a substitute -- and the argument that it will require some team and some level of performance to stop them winning this season's Champions League.

Sources: News Agencies