But although some of Vettel's rivals are refusing to throw the towel in on the season, Massa thinks the title battle is now over.
"I think so, to be honest," he said when asked if he believed it was time to congratulate Vettel.
"I think he will just lose the championship if he stops racing now, and spends months at home only then maybe he could lose the championship. But racing, I think it is very, very difficult for him to lose."
Massa's hopes in the Italian Grand Prix were wrecked by an early-race collision with Mark Webber, which spun him around and left him near the back of the field.
Speaking about the incident, Massa said: "He touched me. He pushed me out so I spun. He stopped after, but I am sure if he did not stop after he would have had a drive through because he just hit me, and he really destroyed my race.
"I think it would have been possible to be fighting with these three guys Fernando, Jenson and Lewis. I managed to pass many cars, and managed to finish sixth, but for sure I could have fought in the top four."