Lewis Hamilton said his Mercedes feels like it is "getting worse" after struggling in Friday's two practice sessions ahead of Sunday's Canadian Grand Prix.
Hamilton is in the unfamiliar position of sixth in the drivers' championship, already 88 points behind rival and defending champion Max Verstappen eight races into what has been a tough 2022 campaign so far.
The seven-time world champion finished fourth last week in Azerbaijan, with team-mate George Russell claiming third, but called the race the "most painful" of his career after suffering severe back pain throughout.
Hamilton's discomfort, which saw him struggle to exit his car after finishing, was caused by the team's W13 car porpoising, bouncing unevenly.
The FIA confirmed on Thursday it had issued a technical directive to teams to provide guidance on how the porpoising problem will be dealt with in the future, with a number of drivers complaining about its effects.
But Mercedes have continued to struggle in Montreal.
Following Friday practice, Hamilton summed up his day: "Pretty much like every Friday for us, trying lots of different things, an experimental floor on my side which didn't work.
"Nothing we do generally to this car seems to work, so we're trying different set-ups; me and George went with much different set-ups in this P2 just to see if one-way works and one way doesn't. I'll wait to hear how it felt for him, but for me, it was a disaster.
"It's like the car's getting worse, it's getting more and more unhappy the more we do to it. I don't know, we'll keep working on it; it is what it is. I think this is the car for the year, so we'll just have to tough it out and work hard on building a better car for next year."
Having won each of the past eight F1 constructors' championships, Mercedes are third in the 2022 standings, behind leaders Red Bull by 118 points.
"It's not the Montreal that I know, that I'm used to and that I've experienced in my career,” Hamilton added. "It's the worse that I've ever felt any car here, so I'm hoping overnight we can try and make some changes.
"But fundamentally, it's just the fundamentals of the car, it is what it is. It's going to be a struggle.
"It's just a monumental fight the whole time to keep it out of the wall.
"When it bounces, when the car leaves the ground a lot, and then when it lands it grips up and it goes in different directions, and you're just trying to catch a car that jumps, hops, grips, hops, grips... it's tough, it keeps you on edge. And there were some big hits today. We've raised the car, but it doesn't make a difference."