The Finn, whose victory for a resurgent Ferrari prevented Lewis Hamilton from clinching his fifth drivers' title in Texas, is leaving the Italian team at the end of the season and, at the age of 39, had been written off in some quarters.
Red Bull's Max Verstappen finished second after starting in 18th place.
The Spanish sensation has now won five championships in motorcycling's premier class, putting him level with Australian legend Mick Doohan.
The world championship leader, who can clinch his fifth title in Sunday's United States Grand Prix, was delighted to hear from his Mercedes team's non-executive chairman who has been recovering after a lung transplant.
The Ferrari ace was reported to the stewards for not slowing sufficiently when the rain-hit opening practice was red-flagged.
Marquez leads Dovizioso by 77 points with a maximum 100 points available from the final four races.
The 33-year-old Briton will clinch his fifth world title on Sunday if he outscores nearest rival Sebastian Vettel of Ferrari by eight points.
Three-time world champion Jorge Lorenzo pulled out of the race after deeming his fractured wrist had not healed sufficiently.
The Spaniard's top five also includes Michael Schumacher, Juan-Manuel Fangio, Ayrton Senna, Alain Prost.
The Silverstone-based outfit did not announce a second driver despite expectations that it will be Canadian Lance Stroll.
Schumacher has qualified for a FIA "super licence", a prerequisite to race in Formula One, and is weighing up whether to move up to Formula Two or higher.
The 19-year-old son of stricken seven-time world Formula One champion Michael Schumacher started the first of three races this weekend on Germany's Hockenheim circuit, the final leg of the season, with a 49-point lead.
The season will start in Australia on March 17.
The incident in May occurred when Raikkonen veered to avoid an oncoming vehicle and collided with a car parked to his right.
Former QMMF and FIA Vice-President Nasser Khalifa Al Attiyah back in action