The fourth Finnish F1 driver was Jyrki Järvilehto a.k.a. JJ Lehto back in 1989.
In 1989 Lehto tested for Ferrari before making his Formula One debut for the Onyx team as a late-season replacement for Bertrand Gachot. Though he failed to prequalify for his first race at Estoril he impressed with his speed in the tough sessions and made his first start in the following meeting. In the wet season finale at Adelaide he ran as high as 5th before retiring with waterlogged electrics. Over the summer Onyx were sold to Swiss racer turned businessman Peter Monteverdi. Lehto, marked by many as a star of the future, was paired with Gregor Foitek but financial difficulties hampered his season, leading to the team's withdrawal after the Hungarian Grand Prix (one of five events the Finn failed to qualify for – though he had been hindered by the team's poor preparation, including a driveshaft being fitted the wrong way around for several meetings, and favouritism towards Foitek, whose father was involved with the buyout).
For 1991 he was signed by the ambitious Scuderia Italia team, financed by Beppe Lucchini with a Dallara chassis, Judd V10 engines and Emanuele Pirro in the second car. Due to poor results in 1990 the cars had to prequalify but soon established themselves as decent midfield runners. In the wet San Marino Grand Prix Lehto impressed by lasting in a race of attrition to finish 3rd, scoring his first F1 points. He impressed elsewhere but did not score again through poor reliability and bad luck (only finishing on four other occasions). He stayed with the team in 1992, now paired with Pierluigi Martini and using Ferrari V12 engines but the new Dallara B192 chassis had severe handling problems. Lehto's best result was 7th at Spa, his worst a failure to qualify at the Hungaroring.
He landed the second seat (alongside Austrian Karl Wendlinger) at the new, much-anticipated Sauber team for 1993, running Ilmor engines. The season started very well as Lehto survived a late downpour at Kyalami to score 5th place on the team's debut, then finished 4th at Imola despite a late engine failure. However, after a collision with Wendlinger at Monaco his relationship with both his team-mate and Sauber became frosty and his season tailed off with no more points scored.
For 1994 he saw off competition from Michele Alboreto and Luca Badoer to land the second seat at Benetton alongside Michael Schumacher. However, he injured his neck testing the new B194 in pre-season with test driver Jos Verstappen taking his place for the first two rounds of the championship. Lehto returned to the cockpit for the ill-fated San Marino Grand Prix despite some question marks over his fitness. He qualified 5th but stalled on the grid, his car being struck from behind by Pedro Lamy's Lotus. This led to the safety car period which may have contributed to the death of three-times world champion Ayrton Senna. Despite running 3rd in Spain before an engine failure and scoring a point in Canada (after the disqualification of Christian Fittipaldi) it was clear his injuries had not healed fully and he was replaced once again by Verstappen for the French Grand Prix. He returned to the cockpit for the Italian and Portuguese rounds in place of the suspended Schumacher but did not impress and was released entirely soon afterwards when the team signed Johnny Herbert. This freed him up to drive in the last two rounds for Sauber – Wendlinger's own injuries had failed to heal and his previous replacement Andrea de Cesaris was unreachable. Lehto's final Formula 1 drives were again mediocre.
