Vettel was squeezed from fourth place, fell back into the pack and was caught in a collision with Brazilian Bruno Senna's Williams that spun him around helplessly facing his speeding rivals.
"There is visible damage, it is not the front wing, we cannot fix it," he was told as he rejoined the chase with the whole race ahead of him.
Four laps later Vettel was assured the data looked good but a concerned-looking Red Bull technical head Adrian Newey had a photograph of the damage taken at the driver's pitstop to get a closer look from the pit wall.
Alonso, Vettel's only title rival who had 13 points to make up, looked like he could steal it as the championship pendulum swung both ways over the 71 laps at Interlagos.
The safety car was deployed twice, there were crashes, collisions, botched pitstops and constant uncertainty about the weather with black clouds overhead, occasional rain but not the torrential downpour many had feared.
Image: Ferrari driver Fernando Alonso, of Spain, celebrates his second place at the podium of the Formula One Brazilian Grand Prix at Interlagos race track in Sao Paulo, Brazil, Sunday, Nov. 25, 2012. Red Bull driver Sebastian Vettel, of Germany, finished sixth to clinch his third straight Formula One championship title on Sunday. Vettel did what he needed to hold off Ferrari's Fernando Alonso, the only other driver contending for the title.