Williams can still challenge Red Bull - Massa

Williams lost out to Red Bull in 2014 and to Ferrari last year, and this season has struggled to compete with both of its rivals.

Red Bull won the previous race in Barcelona to move 29 points clear of Williams in the standings. 

"We know they have a very good car since a long time, in terms of downforce, in terms of corners," Massa said.

"They were struggling with the engine for long time, in the last two years. It's true, the speed they have now is not so far away compared to us.

"Maybe they even improve the car in the corners, and maybe they can improve even more because maybe they get some steps on the engine.

"For sure Red Bull can be very strong from now until the end of the season. We still keep believing that we can fight. We'll see how much.

"I think maybe we will not have the answer here, but maybe in Canada, if they really improve compared to us like they've been showing or not. But we'll keep in the fight."

Asked if Mercedes could dominate the remaining races, Massa admitted he was pleased to see a different winner in Barcelona.

"It's difficult to answer that. For sure Mercedes have an amazing car, so they show in every track. The only track that they didn't win was because both cars were out. They can win here, they can win many different tracks on this aspect as well.

"But Monaco is Monaco, so many things can happen. You never know, so we need to wait and see. It would be nice to have other cars winning like we saw in Barcelona, but we need to wait and understand clearly.

"I think everybody enjoyed what happened in the last race. Maybe not Mercedes! But everybody enjoyed to see different cars winning. We know it's not so easy in F1, there are so many things around, and it's part of how F1 is for a long time."

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