Sauber: "Spiral" was crucial to getting Raikkonen

In the summer of 2017 Sauber cancelled a planned Honda engine deal and inked a new arrangement with Ferrari that gave it the use of a latest-specification engine after spending that season with a year-old unit.

Since then, it earned a title partnership with Alfa Romeo, fielded Ferrari protege Charles Leclerc in his rookie season and made major staff hires including Ferrari man Simone Resta as technical director and Audi aerodynamicist Jan Monchaux.

Sauber dovetailed this off-track progression with significant improvement on-track and snapped up 2007 world champion Raikkonen on a two-year deal once the Finn learned he would be replaced at Ferrari by Leclerc.

Team principal Vasseur said earlier in 2018 that Sauber's Alfa deal had made it much more attractive and that signing Raikkonen had a similar motivational impact.

He told Motorsport.com that the sequence of positive events created an atmosphere that made Sauber attractive to Raikkonen, who will partner Antonio Giovinazzi in an all-new line-up.

"We had Ferrari, Alfa Romeo, we had Charles joining the team," said Vasseur. "We took Jan Monchaux, Simone Resta, brought them into the factory.

"Each week we had good news, it's like a spiral. The motivation is there, the mood is huge compared to last year, the team spirit."

Vasseur said the "appetite for the team was completely different for recruitment and for sponsors" after its "crucial" Alfa Romeo partnership was announced.

"For me, drivers are the same," Vasseur added. "Good engineers you can motivate with the salary but they love racing and they want to get results.

"We're in a much better position to recruit, to have top guys in every single department. I have the feeling that we're really attractive as a project.

"Drivers are the same story. Kimi knows it will be difficult for us to better than P7 without an accident [for bigger teams].

"The motivation can come from somewhere else. The fact we're improving, we're growing up, we're building something – I think it's a huge feeling for all the team members, including drivers."

Vasseur said Sauber's recruitment plan was not yet finished as it bids to follow up on a strong 2018 by becoming a season-long top-10 threat.

He claimed that the results in 2018 were only the "first results" of its staffing push.

"We recruited a lot since last year to improve on every single part of the company and it's paying off," he said.

"When we started to work at the end of '17, people joined at the beginning of '18 and some of them were working on the '18 car.

"Some of them switched directly to next year's car. It's the first results of this recruitment. I hope it will get more and more."