Manchester City manager Pep Guardiola has admitted ahead of the formidable challenge of facing Barcelona without a recognised right back on Tuesday night that his former team’s wide players are virtually “unplayable.”

City’s 4-0 defeat at the Nou Camp two weeks ago leaves them with four points from their opening three Champions League matches and potentially under serious pressure to avoid group stage elimination if they lose at the Etihad, with Borussia Monchengladbach and Celtic still to play. Facing Lionel Messi and Neymar without a recognised right back makes the challenge even harder.

“I think that we have to think we’ve not got a right back. We’ve got one who recently played there and one who is 19,” said a markedly subdued Guardiola, who has clearly been stung by the scoreline in Catalonia. Without either Pablo Zabaleta and Bacary Sagna to select from, he must weigh up the merits of Fernando, an effective emergency right back at West Bromwich Albion on Saturday, or teenager Pablo Maffeo. Maffeo shackled Manchester United’s Marcus Rashford in last week’s EFL Cup tie but is unlikely to be thrown in against the Spaniards.

The Spanish champions will be without skipper Andres Iniesta, as well as defenders Gerard Pique, Jordi Alba and Jeremy Mathieu, but Guardiola admitted that his side must play their “perfect game” if they are to win and admitted that he could not make up the quality deficit between the sides in just three months at the helm.

City’s task is rendered tougher by the absence of goalkeeper Claudio Bravo, suspended after this dismissal in the Nou Camp – the side’s fourth sending-off in their past five Champions League matches against Barcelona, all of which they have lost. Guardiola believes they must learn better discipline if they are to break that cycle of defeat and record their first Champions League win against Tuesday night’s opposition.

“You have to learn,” Guardiola said. “It’s always difficult to win Champions League games, it’s always difficult against Barcelona 11 v 11, when it’s 10 v 11 it’s almost impossible. Manuel [Pellegrini, the former City manager] lived [through] that, sometimes [the red cards were] unfair, last time it was from a [Bravo] mistake. But at that level it’s impossible to achieve your targets [if you fail to maintain discipline]. It’s football. Football is a game of mistakes. But I completely agree [about the need to demonstrate discipline].”

Guardiola dead-batted potentially inflammatory questions. When asked about the latest visceral attack on City by Yaya Toure’s agent Dimitri Seluk, who says his calls to Guardiola about the player have gone unreturned, he replied flatly: “No answer. No answer. No answer.”

When asked about his comment that he was a Barcelona fan and that playing Luis Enrique’s side would therefore be difficult, he said: “No. No.”

Willy Caballero has enjoyed a resurgence under Guardiola (Reuters) (Reuters)

Bravo will be replaced in goal by Willy Caballero, a popular and charismatic member of the squad for whom Guardiola provided a warm tribute. But the City manager hinted that the Argentine had his fallibilities.