Felipe Massa says his two left rear punctures during the opening practice session for the Chinese Grand Prix were caused by contact with his car's bodywork.
On both occasions Massa suffered deflations smoke was seen coming from the tyre in the corners beforehand. The Brazilian is unsure of the specifics beyond the tyre touching another part of the car.
"We had two punctures," Massa told Sky Sports. "Why, I don't know. We are investigating why we are having this problem. For sure something is touching the tyre or the wheel or whatever. So we need to understand."
The second failure was almost a mirror image of the first, with an irritated Pat Symonds, the team's technical chief, leaving the pit wall on Massa's return to the garage. Massa says the second failure was the same as the first.
"We had no idea why we have this first problem," he said. "So we checked this car, everything was OK, so we went again. And then we had the same problem again on the out-lap which I was slow so for sure something is touching the tyre which we don't understand why."
While both Massa's failures led to red flags, Renault's Kevin Magnussen soon returned to the pits with a left rear puncture of his own, appeared to be caused by debris left by the Williams. Tyre supplier Pirelli and the teams are continuing to investigate all three incidents.