Donnarumma signed for PSG in the off-season, as one of four remarkable free signings alongside Lionel Messi, Georginio Wijnaldum and Sergio Ramos.

It is fair to say that none of those additions have been rip-roaring successes. Messi has failed to replicate his Barcelona form and scored only seven times across all competitions, albeit that does make him PSG's second-highest goalscorer so far this season, behind Kylian Mbappe (26).

While Messi has at least provided 10 assists, Wijnaldum has only directly contributed to six goals in all competitions (three goals, three assists), creating just 11 chances for his team-mates. Due to persistent injury concerns, Ramos has made just five appearances in total, playing 284 minutes.

Donnarumma, meanwhile, has had to vie with Navas for a place as PSG's first-choice goalkeeper.

The Euro 2020-winning shot-stopper did not make his Ligue 1 debut until 11 September, and has started on just 12 occasions in France's top flight, having been a substitute in another 12 league games.

Two further appearances have come for Donnarumma in the Coupe de France, but the latter game saw PSG eliminated on penalties by Nice. The 23 year-old has played in five Champions League matches, but was culpable for Karim Benzema's first goal on 9 March as Mauricio Pochettino's team capitulated against Real Madrid in the last 16.

In the opinion of Barthez, who played a pivotal role in France's 1998 World Cup triumph, having two top-quality goalkeepers at the club is actually backfiring on PSG.

"I respect coaches a lot, I respect Pochettino a lot and I know how difficult this job is, but putting two goalkeepers of this level in competition [with each other] does not serve the team," he told L'Equipe. "What message are you sending to your goalkeepers? What psychological dispositions do you place them in? Who do you really trust for big games? What do outfield players say to each other?

"You instil doubt in everyone and then, it's the competition that makes you progress, not the training. A guy like Donnarumma - or Navas for that matter - he has to play. What happened [against Madrid] is the consequence of all that."

Donnarumma has made 61 saves, 10 fewer than Navas' 71, across 19 games in all competitions, although the Italy international has registered a better save percentage compared to his Costa Rican counterpart (78.2 in contrast to 76.9).

When taking goals prevented into account, based on Opta's expected goals on target conceded (xGOT) model, Donnarumma also has a clear edge, having prevented a total of 4.8 goals in comparison to Navas' figure of 2.8.

Essentially, Donnarumma's saves have prevented a further two goals than those of Navas, and Barthez has backed the former Milan goalkeeper to improve.

However, he believes Donnarumma "lacked humility" when he made the mistake that allowed Benzema to kick-start a comeback that dashed PSG's Champions League hopes at the Bernabeu.

"I adore him, I have observed his performances for a long time. But on this one, he also lacked humility," Barthez added. 

"But, in a way, what happened to him makes sense. He wins the Euro, he is full of confidence, he arrives in Paris and we put him in competition with Navas."