With no substantial upgrades to the car since pre-season testing, apart from the Ferrari engine's new spec arriving this weekend, the Swiss team is working hard to bring improvements.

However, with a shortfall of budget, Nasr is not certain how soon the upgrades can be finalised and introduced.

"Difficult times, that’s the reality for us at the moment," said the Brazilian.

"It is what it is, I am sure the team is trying hard to improve the situation.

"We have upgrades planned on the car, but for them to do that, they need the financial resources."

Nasr revealed that Sauber is aiming to bring an update between Canada and Britain, but admitted he was not aware of the exact details.

"We had a plan to bring updates around round seven [Canadian GP] and round 10 [British GP], but I don’t know what's the latest on it."

Ericsson pessimistic

Teammate Marcus Ericsson hopes the new Ferrari engine, featuring an update to the ERS, will bring a performance lift for the Sauber C35 - but says other updates "won't come anytime soon".

"It is not ideal [for sure], every other teams bring upgrades to Barcelona and we only have the Ferrari's new engine," he said.

"I think we need a new aerodynamic package, the wings and the floor, it is the same we had in testing, it is the same that we had at the end of last year.

"So I know, it is in the loop to get on the car soon, but how soon it is difficult to say, but for sure we need as soon as possible to be more competitive.

"It is being worked at but it won’t come anytime soon."

Additional reporting by Oleg Kaprov