Felipe Massa says drivers, teams and fans will have to wait until qualifying for the opening round of the 2015 Australian Grand Prix to get an idea of who will be competitive this year.

The Brazilian returned to the cockpit of the Williams FW37 at the Circuit de Catalunya, producing the third fastest time and completing a solid 88 laps in the Mercedes-powered car.

Following the outfit's strong 2014 season and a seemingly positive start to 2015 testing, Williams are being tipped as a team to watch once again. However, Massa says it is still far too early to start predicting the order and that it won't become clear until the opening round.

Related Articles

"It is a bit early to say where we are compared to the others, but we will keep pushing," he said. "The car has good potential, but you feel where you are when everyone is on the same fuel or everyone is on the same tyres.

"Even if you feel your car is good, but then people are doing quicker lap times than you it is different. I don't think it is the case but when we go to Australia in qualifying we will understand where we are compared to the others. I think it is going in a positive way.

Comparing the FW37 to its predecessor, Massa feels there has been a step forward in competitiveness, particularly in areas where last year's car struggled.

"We feel some improvements compared to last year," he said. "There were some areas where we weren't very strong, but we are still trying to put as many new parts on it before Australia, so we still need to understand step-by-step. For the moment, we are still working, understanding and improving day-by-day."