Mercedes insists there is no "panic" behind closed doors, but key rival Red Bull's Dr Helmut Marko says the German team is tackling "several" problems with its new car.
"It's not one problem, it's several problems," Marko, 79, told the German broadcaster ntv.
"The solution didn't come over the winter, either, which I'm rather surprised about."
Indeed, Mercedes has taken the unusual step of publishing an open letter to its fans rejecting widespread rumours the newly-launched car is set to be scrapped.
"We won't panic or make knee-jerk reactions," the letter read.
"We have been open and searingly honest about where we find ourselves. And we are working urgently and calmly to build our recovery plan, focusing on what needs to happen short term, medium term, and long term to win.
"We already have developments in the pipeline for the next races - and there will be more to come. But this won't be the work of a moment; there are no silver bullets in F1," Mercedes added.
While visible changes may be seen as soon as this weekend in Jeddah, the first major changes - including the appearance of Red Bull-like sidepods - are rumoured to be due by Imola in May.
"Conventional updates that bring a few points of downforce won't catch us up with Red Bull," Wolff admits. "We need big steps because we're a long way away."
Red Bull's Marko, however, thinks Mercedes will struggle to make the necessary sweeping changes under the confines of the budget cap.
"You are simply limited in your options now," he said. "You can't design two or three cars in a year.
"Even if a completely new car comes, now, then it will be difficult afterwards because of the financial limitations.
"In this respect, I think it's realistic to say the world title is out of reach for Mercedes," Marko insisted.
New Ferrari boss Frederic Vasseur, on the other hand, has higher hopes for the Brackley based team.
"Mercedes will wake up, and soon," he said.
"Already in Jeddah - different circuit type, different surface - the picture could be completely different."
