Jose Mourinho slouched in his chair on the touchline, seemingly unable to believe was playing out in front of him.

He wasn’t the only one.

His Premier League champions had fallen to a defeat thanks in part to a 16-year-old striker who probably should have been in bed rather than putting the frighteners up a defence which included club captain John Terry.

Tyler Adams, born in 1999, will forever remember the evening he brilliantly headed past Asmir Begovic to help a Red Bulls team packed full of reserve and youth players ensured Mourinho's pre-season campaign began with an uncomfortable, lackadaisical defeat.

The plane journey back to their Montreal base would not have been a barrel of laughs.

In control for 50 minutes of this bewildering match Mourinho, who made eight changes at half-time, and will rightly cite summer rustiness as a cause of their travails, saw his English champions struck by four goals in quick fire succession, the best of which taken by the precious talent of Adams.

Naturally, the Portuguese will not lose too much sleep. Yes his charges were sloppy and without doubt, they were sluggish and ultimately disappointing.

Yet it's their first match. Performance levels are sure to be accelerated in North Carolina against PSG on Saturday. They will have to be following this chastening night for those in Chelsea blue.

“They were sharp , quick high motivation, very happy to play against us and they gave us a better match then we thought,” said the Portuguese.

“I am the manager of the best team of England, we have top players, there are no fragilities. We have done 11 sessions in six days. We trust these players. We play this team 10 times we win nine but the second half was a disaster.

“If we had won 10-0, that wouldn’t have been any good. We needed a test and we received one.”

Thanks to the peculiar, often mind-boggling vagaries of the MLS schedule, the Premier League champions began their three-match North American tour against what was effectively a New York Red Bulls reserve team.

Their coach, Jesse Marsch, quite understandably gave all the first-teamers the day off following the US Open Cup defeat to Philadelphia Union coming just 24 hours earlier. His side were packed full of youthful endeavor and exuberance. How they relished this challenge. “It was an incredible result for us as a club,” purred Marsch. “Tyler is finishing high-school and is with the U-17 national team. He is very alert and not afraid. He has a very big future.”

Chelsea’s tour thus far has been pretty low-key. This, however, certainly upped the ante a few notches.

There have been no fanfares echoing out of their Montreal base.

Mourinho's starting line-up however showed he meant business. Thibaut Courtois, Cesc Fabregas and Oscar all started while the likes of Eden Hazard, Diego Costa and John Terry were primed to come off the substitutes bench.

It was a vastly inexperienced Red Bulls side, yet one full of youth and worry-free endeavor who contained their illustrious visitors to one solitary chance in the opening 15 minutes, French striker Loic Remy denied from close range by Kyle Reynish.

John Obi Mikel, given the role of marauding midfielder, to show Mourinho he's worthy of a continuing role in the first team squad place despite interest in his signature from the Middle East, should have scored on 20 minutes, yet his header from an excellent scooped center from captain for the evening Branislav Ivanovic rolled the wrong side of the post.

Mourinho began prowling, and scowling, on the touchline. Even when Remy opened the scoring on 26 minutes, the Portuguese barely moved a muscle.

It was move, perhaps, worthy of even the smallest of claps or fist pumps. A curling through ball from Victor Moses set the sprightly Oscar skipping down the right and the Brazilian's center found Remy who, this time, clinically did the rest.

The Frenchman himself would have been content. Mourinho revealed last week that the former Newcastle forward, who had been courted by Crystal Palace and West Ham, was not for sale at any price, urging him to provide a selection headache in attack.

Costa remains the Portuguese’s go-to man yet the effect Falcao will have remains an unknown. There is a chance for Remy to shine and he was on his mettle here. Courtois, mainly a spectator, was almost embarrassed three minutes before the interval when a backpass to his weaker right foot almost resulted in a calamity before the Belgian regained his composure and averted danger.

Changes were predictably rung at half-time with big hitters Costa, Hazard, Terry, Nemanja Matic and Ramires all introduced while Begovic, signed as a replacement for the Arsenal-bound Petr Cech, was also given his first taste of action in Chelsea colours.

And within five minutes, his debut had turned into a nightmare. A woeful backpass from Terry left put the Bosnian in all manner of problems, a combination of slow reactions and being caught unaware by the club captain’s uncharacteristic mistake allowed Franklin Castellanos to gleefully slide the Red Bulls level. “Both keepers were tired, they lacked agility but I am not worried,” added Mourinho.

The goal sparked the home side into action yet the clearer cut chances continued to fall to Chelsea - Costa heading against the bar on 62 minutes before failing to convert the rebound.

The plucky Red Bulls weren’t finished however. This time Castellanos turned provider for Adam to head past Begovic - so poor was the defending that Mourinho instantly hauled off substitute Ola Aina.

When Davis made it three on 73 minutes, it was scarcely believable.

Hazard pulled one back two minutes later yet more appalling defending ensured Davis scored his second of what was fast becoming an inconceivably frustrating evening for Mourinho.

It was a match the 16-year-old Adams in particular will never forget.

The Portuguese, however, will banish it his mind as soon as humanly possible. In fact, he’s probably already forgotten it.

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