Complex sentence: Kimi Räikkönen, driving for McLaren-Mercedes, and Juan Pablo Montoya, driving for BMW Williams, both had a chance of claiming the 2003 championship until late in the season, with Räikkönen still mathematically in contention at the final race, the Japanese Grand Prix.
Split into simpler sentences: Kimi Räikkönen, driving for McLaren-Mercedes, and Juan Pablo Montoya, driving for BMW Williams. Both had a chance of claiming the 2003 championship until late in the season, with Räikkönen still mathematically in contention at the final race, the Japanese Grand Prix.