Marseille came out fighting on Sunday following coach Marcelo Bielsa's shock resignation, accusing the Argentine of trying to hold them prisoner.

A strongly-worded club statement claimed: "Marseille possess a sufficiently rich history to refuse to surrender to the rule of one man".

The French giants insisted they wouldn't be "held prisoner by a man who places his personal interests high above those of the club" in resigning after Saturday's Ligue 1 curtain-raiser, a 1-0 home loss to Caen.

The attack on the man known as 'El Loco' (the mad man) came less than 24 hours after he had delivered what captain Steve Mandanda described as his "hammer blow".

"I have resigned from my post as manager of Marseille," the 60-year-old told a stunned post-match news conference after the season-opening 1-0 home loss to Caen.

He blamed last minute changes to his contract for the decision which left Marseille president Vincent Labrune dumbfounded.

"I am, like all the supporters, dazed by Marcelo Bielsa's shock decision," Labrune declared in a statement released early Sunday.

"However, we take note of this decision which places the club in a difficult place having started the new season with a home defeat," Labrune added.

He confirmed that one of Bielsa's assistants, Franck Passi, would step up as caretaker coach pending a permanent replacement.

The club and owner Margarita Louis-Dreyfus assured fans they would "take all necessary measures in the coming days to enable Marseille to enjoy a season to the height of its expectations".

Bielsa in his resignation rocket wrote: "I am sad and frustrated.

"I cannot accept the situation of instability at the club.

"We had reached an agreement on a contract extension for 2016-2017, which was missing just a signature."

Bielsa said he had met Wednesday with the club's chief executive Philippe Perez and Igor Levin, Louis-Dreyfus's lawyer.

"They wanted to change the contract," he complained.

"I took this final decision as working together requires a minimum of trust, which we do not have."

And in a direct barb at Labrune he concluded: "Even if I don't think you wanted this, what's happened comes with your authority, I think you know what's gone on."

Labrune questioned Bielsa's version of events.

"I find it hard to understand how a straightforward meeting on Wednesday about the finer points of this contract could be behind this precipitous decision despite all his demands having been met."

Bielsa, who guided Chile to the last 16 at the 2010 World Cup, was at pains to point out his abrupt exit had nothing to do with money, revealing he had turned down a new deal multiplying his salary threefold.

And he said he'd been patient with the club, despite uncertainty in the way they had conducted themselves in the close-season transfer market.

Mandanda spoke for his astonished teammates, describing Bielsa's departure as "a massive hammer blow".

"At Thursday's press conference, everything was fine, it was all positive," the France international goalkeeper added.

"He was an important part of the club, for the team. We are disappointed. We don't know the ins and outs of it, we don't know what has happened. But we respect his decision.

"He developed almost the entire squad. And what's delicate about all this, there are players who came here because of him.

"We all got on well with him, with a good game plan compared to past seasons.

"But he's made his mind up, and we just have to accept that."

Quizzed on what Labrune had told the team Mandanda said: "He told us he was above all disappointed because he's still a great coach who made us all grow. He is remaining composed."

Teammate Florent Thauvin added: "We haven't seen Bielsa but we had a chat in the changing room with the president who reassured us, we're not going to dwell on it, we have a season ahead of us."