Felipe Massa was pleased to lead Williams into the Formula 1 points in Sunday's United States Grand Prix as he finished ninth, but felt he could have passed Sergio Perez for P8 had it not been for blue flags late on.

Massa made a bold strategy work by completing the final 27 laps of the race on the ultra-soft tyre, allowing him to gain ground on Perez through the closing stages as the Force India struggled to keep life in his soft compound Pirellis.

Massa was within DRS range and able to put pressure on Perez in the final few laps, only for blue flags for the leading drivers to force the Brazilian to back off and settle for P9 at the chequered flag.

"It was definitely a good result. It was a good race, and points were always what we were looking to achieve," Massa said.

"We lost a few points to Renault, but it was a positive race and I’m happy with the result.

"Unfortunately, the blue flag took away my opportunity to overtake another car at the end and take eighth instead of ninth, but I’m happy with the race and the job I did. That’s the most important thing."

Williams remains fifth in the F1 constructors' championship, 15 points clear of Toro Rosso and 20 ahead of Renault with three races remaining.