Lionel Messi had been a peripheral figure in the second half at the Parc des Princes. But, as Manchester City pushed for an equaliser, he was watching and waiting for his moment.
It came in the 74th minute, when, still positioned inside his own half on the right-hand side of the pitch, Messi collected Marco Verratti's pass and surged into the space in front of him.
By then, it already felt like something special was about to happen.
Achraf Hakimi's overlapping run distracted Joao Cancelo and Messi charged inside, ghosting past Aymeric Laporte as though he was not there, bouncing a one-two off the heel of Kylian Mbappe's right boot, then firing a brilliant first-time shot into the top corner.
The stadium erupted and the intensity of Messi's celebration betrayed his relief. He had started slowly in his new surroundings, failing to score in his first three PSG appearances then suffering an injury, but now he has truly arrived.
Moments like this are precisely what he was brought to PSG for, but this was not a vintage Messi performance.
There were some eye-catching passes, most notably the one to release Nuno Mendes on the break while under pressure in his own half in the opening period, but he did not create a single chance over the course of the game. He only managed one successful dribble and did not have a single touch in City's box.
Even in those circumstances, though, stationed out on the right and closely marshalled by one of Europe's best defences, Messi found a way. His goal, beautifully taken from 20 yards out, came from his only shot of the evening.
It was a reminder, if it was really needed, of the genius that still allows him to settle the biggest games. It was a reminder, too, of how his signing elevates a side seeking their first Champions League crown. On this evidence they will take some beating.
There is no need for Manchester City to panic after this defeat. There are four games to go in the group stage and, having beaten RB Leipzig in their opener, they are only one point behind PSG.
Pep Guardiola was keen to convey a sense of calm in his post-match interview. "Now we are going to eat well tonight, we are going to drink a glass of wine, we are going to recover and we are going to prepare for the game on Sunday," he said.
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But at the same time he will be aware of the need for his side to demonstrate more cutting edge if they are to overcome Liverpool in that Premier League meeting at Anfield.
At the Parc des Princes, they had 18 shots without finding the net. Bernardo Silva was most culpable, striking the crossbar from a few yards out when it looked easier to score in the first half, but he was not the only one who lacked composure when it mattered.
The same was true of Riyad Mahrez, Kevin De Bruyne and Ruben Dias, all of whom spurned good opportunities to beat Gianluigi Donnarumma.
There have been other occasions this season, of course, when they have had no trouble finishing off their chances. But this was one of those performances which shows why Guardiola was so keen to sign Harry Kane from Tottenham during the summer.
Last season, City did not fail to score in any of their first 15 games of the campaign. This time, it has already happened three times in nine. At Anfield they will need to be sharper.
There was no surprise that Mohamed Salah, Sadio Mane and Roberto Firmino were the scorers in Liverpool's 5-1 win away over Porto in the Estadio do Dragao on Tuesday. But the identity of the players who set those goals up will have satisfied Jurgen Klopp.
James Milner, Liverpool's oldest player, deputising for the injured Trent Alexander-Arnold, delivered the measured cross that found its way to Mane at the far post for the second. That aside, it was Curtis Jones, their youngest starter, who was the star of the show.
Jones set up three of the five goals and did so much more, with and without the ball, to underline his growing importance to this Liverpool team. He was the catalyst.
Klopp had been gesturing for his players to speed up the play as they stroked it around the back with the score goalless midway through the first half. Jones did rather better than that. Recognising the space was out wide, he drifted in search of it and drove at the defence.
It was a moment of quality and showed that the 20-year-old midfielder is prepared to do more than just play it safe, tick the ball over and wait for the big names to deliver. He has that swagger, that appetite and ability to make things happen himself.
Jones can still do the simple stuff too. Yes, there was one languid ball forward and a failed attempt to angle a pass in behind when he spotted Salah in space, but those moments stood out for a reason. They were the only two times in the first half that he misplaced a pass.
Forty others found a team-mate in that 45 minutes, his passing accuracy the best of anyone on the pitch. His total of 28 completed passes in the opposition half before the interval was also more than anyone else. It was a performance that demanded attention.
Harvey Elliott had much of that at the start of the season, stepping into that place left vacant by Gini Wijnaldum's exit. Jones is more familiar, having already registered over 50 appearances for Liverpool. But on this evidence he looks ready for a bigger role.
His work for the third goal illustrated that best. Winning the ball was great, running with it was good too, but the presence of mind to pick out the right pass was even better.
The fourth owed something to some miserable goalkeeping after Jones sent the ball down the left channel more in hope than expectation but he had done well to retain possession in a tight spot before that. He was even involved in the fifth.
It capped what was a wonderful night for him. While Milner impresses by maintaining his level, Jones might just be finding a new one.
On a night of high drama in the Champions League, Moldovan side Sheriff Tiraspol pulled off one of the biggest shocks in the competition's history as they beat Real Madrid 2-1 at the Bernabeu.
Sheriff, who come from the unrecognised breakaway state of Transnistria and upset the odds to even reach the group stage for the first time, emerged victorious in the Spanish capital thanks to superb 89th-minute strike from Sebastien Thill.
Earlier, they had taken the lead thanks to a header from Uzbek midfielder Jasurbek Yakhshiboev, with Real Madrid requiring a Karim Benzema penalty in order to pull level.
The Spanish giants peppered the Sheriff goal, attempting 31 shots to the visitors' four and having 76 per cent of the possession, but they failed to take their chances and were punished in sensational style.
Sheriff, who had already stunned Shakhtar Donetsk with a 2-0 win in their opening Champions League game, now sit top of Group D with six points - and a genuine chance of reaching the last 16.
"It's hard to explain the game," said a stunned Carlo Ancelotti afterwards.