NAC are reeling after their 8-0 home defeat to Ajax - the worst result in the club's history.
On-loan City defender Mari admits NAC will be holding crisis talks on Sunday.
"Tomorrow is the time to tell everyone what is important to him," says the NAC captain. "We have all failed, no one excepted, it is good to put everything on the table and say everything to each other."
Meanwhile, NAC coach Stijn Vreven says he'll take responsibility for the performance.
"This was an embarrassment, a shameful display that we did not see coming. We did not really fit in all areas, it was not a game for a moment, we only have a chance against a top team when we show passion and fight, and that we did not do today," he said.
"The shame lies mainly in the fact that we show this to nineteen thousand fans, who support us every week."