Felipe Nasr fears Sauber will face ongoing issues for a number of grands prix at the start of the 2016 Formula 1 season.
Nasr departed Australia baffled by the handling performance of the C35, notably as it struggled under braking and on turn in, areas the Brazilian felt comfortable with following pre-season testing.
The overall lack of pace within the car was his primary concern after qualifying 17th at Melbourne's Albert Park and finishing the race a lap down in 15th.
"To be honest we are lacking pace on the car, we are lacking a lot of performance compared to our other competitors," Nasr told Autosport.
"There was no way we could have finished the race in the points. It was way too far for that, which means we have a lot of work to do.
"Hopefully we can bring updates as soon as possible. There are many areas we should improve because we are talking pure, pure performance."
Nasr concedes he was under no illusions just how acute the problems were, and recognises they are unlikely to all be rectified quickly.
"Going into Australia I didn't create any expectations," added Nasr.
"I was being very realistic. I knew we would face a difficult opening round, and I think it will be like that for a few races.
"We are going to be facing some difficulties until we do get this car updated, and I mean bring more downforce to the car, setting it up right and getting a proper rhythm on everything.
"In the Barcelona test we only had one chassis there, and it was Marcus' [team-mate Ericsson] car. Mine only got done on the Wednesday before Australia.
"We had no time to shake it down, the roll-out was FP1, but we could not get everything in the background to set it up 100 per cent.
"There are still some things we can do, homework, and hopefully we can bring this performance back to the car and try to fight for the upper places on the grid."
Nasr's concerns are highlighted by the fact the other teams in the lower midfield last year all appear to have made progress this season, with Sauber's recently highlighted financial problems also a worry.
"For sure, they [the other teams] have taken a much bigger step than we thought," said Nasr.
"There is a lot to catch-up on our side, and on the financial side we are still struggling on that.
"But hopefully we can make up on things.
"We need to start adding more performance in the car. That is what we are looking for."