Manchester City have called for the cavalry and, based on the evidence of Wednesday night at Paris Saint-Germain and numerous other performances over the past few months, it cannot arrive quickly enough. Something is missing within the serial Premier League champions and it was revealing to hear Jack Grealish reach for a word that has routinely been associated with them; with the winger and his own game, too. Swagger.

At times like these, with City’s title defence in flames and their Champions League hopes heading to the wire and a must-win home tie against Club Brugge on Wednesday, it is inevitable that confidence will be affected. What Grealish and everyone connected to the club hope is that a concentrated and explosive spending burst can provide a psychological lift, as much as anything else.

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“It’s down to us to get that confidence and swagger back,” Grealish said after the 4-2 defeat by PSG, when City threw away a 2-0 lead; yet another lead. It was the ninth time this season they had led and not won, the third time in four Champions League games. “We have new signings coming in and hopefully we can get our confidence back,” Grealish said.

Pep Guardiola has admitted it was probably a mistake not to have strengthened more last summer, particularly after the sale of Julián Álvarez. Only Ilkay Gündogan and Savinho were added. Hence the reactive £122.5m spend this week, starting on Monday with the arrival of Abdukodir Khusanov for £33.8m from Lens, running through Tuesday’s signing of Vitor Reis for £29.6m from Palmeiras and peaking with Thursday’s confirmation of Omar Marmoush for £59.1m from Eintracht Frankfurt.

It has not mattered to City that January is a notoriously tricky time to do business. They have simply stumped up and got things done. Khusanov and Reis are 20 and 19 respectively, Marmoush older at 25, and the first thing to say is that it would be foolish to pin too much, too soon on the trio.

Two are young and each is moving to a new league in a new country. On and off the pitch, the cultural differences will be stark. And they are joining a club at the lowest ebb of the Guardiola dynasty, so many of the previous certainties having been eroded.

The lack of confidence is only one part of the problem and it is not a root cause, rather a byproduct of something else. Maybe a shot of youthful energy is what City need because they looked creaky and tired against PSG as the tie wore on, especially in midfield.

The worry for City’s fans is that Khusanov and Reis are central defenders, Marmoush a player for the front line. None will directly address the major problem area at the Parc des Princes. On the other hand, it is understood that City’s January spree may not be over. A midfielder has to be the priority.

The PSG game started to get away from City when Bradley Barcola did precisely that to Mateo Kovacic. After tricking past the stand-in City right-back, Matheus Nunes, Barcola was simply too fast for Kovacic, easing clear up the inside left before squaring for Ousmane Dembélé, on as a substitute, to make it 2-1. And here is the thing – Kovacic is probably City’s hardest midfield runner.

Guardiola wanted to dictate possession and, by extension, the tempo, beginning at the back. “To defend with the ball,” as he put it. He said it was necessary to “keep the ball, make an extra pass”. He wanted to connect up through Kovacic and Bernardo Silva, his starting central midfield pair.

But it became impossible in the face of PSG’s sheer physicality, the speed and hustle that they brought. “After 2-0 and especially 1-2 we could not play,” Guardiola would exclaim. There was no respite and – one of the themes of City’s testing season – no control. City were also vulnerable to PSG’s quick transitions. “We could not cope with them,” Guardiola admitted.

He talked about how PSG had an extra man in midfield because of Luis Enrique’s deployment of a false 9 – Lee Kang-in during the first half, Dembélé from the beginning of the second period. But Luis Enrique introduced a purer No 9 in Gonçalo Ramos on 61 minutes, straight after Barcola had scored for 2-2 and that was the point at which PSG really started to run through City.

Guardiola withdrew Kovacic and Kevin De Bruyne, who played in the No 10 role, on 70 minutes, introducing Gündogan and James McAtee. It did not work. PSG had the wind in their sails, their momentum irresistible. Up in the stands, Rodri watched it unfold. It was the latest illustration of how City miss their injured linchpin.

“I had a good feeling when we were 2-0 up,” Grealish said. “Usually it’s when we are at our best … we keep the ball well, manage it and see the game out but we didn’t do that at all. We didn’t keep the ball well.”

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Guardiola’s post-match assessment went beyond a step-by-step expose of his team’s shortcomings. He also mentioned “survival” – and not for the first time. As in, the mode into which City are being forced to click. It will be the name of the game against Brugge.

City know that victory would guarantee they advance into the playoff round, rather than exit the Champions League at the first hurdle for the first time since 2013. Brugge may need something, too – a draw to make sure of their own progress into the playoffs – but there is a significant difference. The team that sit second in the Belgian league have a recent record in all competitions that reads: W15 D4 L0. The confidence will belong to them.