Felipe Massa has been back behind the wheel of his kart this week fuelling speculation that he might return to F1 before the end of the season.

Originally it was thought that Massa would not return to F1 duty until next year, however, speaking at the weekend Ferrari team boss Stefano Domenicali hinted that the Brazilian could make an early return. This followed the Brazilian's own announcement that he is planning to race in the International Challenge of the Stars in November.

Massa was back in action on Monday though heavy rain meant the session was brought to a close after just 7 laps. The Brazilian's return was supervised by his personal doctor, Dino Altmann, who has advised that the driver should spend no more than an hour in the kart in order to avoid back pain.

Yesterday, however, the 28-year-old was back on duty at the Granja Viana track near Sao Paulo accompanied by his brother Euardo, and was able to complete significantly more laps.

It is understood that Massa, who wore extra protection above his left eye, felt fine and experienced no problems.

Following further tests this week in his kart, next week, Massa is scheduled to fly to Maranello where will use Ferrari's static simulator.