MONZA Italy (Reuters) - Finland's Valtteri Bottas and Brazilian Felipe Massa will stay at Williams in 2015 after the resurgent Formula One team announced on Sunday what had to be one of their easiest decisions of the season.
"It was easy to make that choice," acknowledged deputy principal Claire Williams ahead of the Italian Grand Prix at Monza. "I think they have both shown they can deliver what we need them to."
Massa joined Williams from Ferrari at the end of 2013 while Bottas has been with the team for five years, making his race debut last season, and emerged as a standout performer in a championship that has seen Williams back among the leaders.
The former champions were fourth overall in the championship ahead of Sunday's race with 150 points after scoring just five last year.
Bottas, 25, is fifth in the drivers' standings and has finished on the podium in four of the last five races. He and Massa qualified together on the second row of the grid on Saturday.
"The team is having a much improved 2014 season and the skill of our drivers and their feedback to our engineers has proved crucial in this," said team founder Frank Williams, who described Bottas as an 'investment' for the future.
"This announcement gives us excellent stability for 2015, but of course we are very much focusing our attention on maximizing the full potential of the FW36 in the remaining seven races of this season."
Claire, his daughter, felt the drivers were capable of mounting a championship challenge if Mercedes-powered Williams could provide a car good enough.
"One hundred percent," she said. "That is the goal, to win that championship and of course you are going to put the drivers in your cockpits that you believe can do that."
The team are the second most successful in terms of constructors' titles after Ferrari, with nine between 1980 and 1997, and last won a grand prix with Venezuelan Pastor Maldonado in 2012.
Their last drivers' title was with Canadian Jacques Villeneuve in 1997.
"We want stability at Williams," said Claire Williams, when asked whether other drivers had been considered. "We went into this season wanting stability into the long term and that's what we have now.
"I think we've got one of the strongest lineups on the grid, they've got really complementary talents - Felipe with all his experience and having worked in a big team and Valtteri who's got this amazing natural talent."
The deputy principal said the objective, as ever, was to get back to the top and that remained a tough challenge.
"It's relatively easy to turn around a team that's ninth and take it up to fourth but when you are in fourth and want to start challenging for a championship it's a whole different piece of work," she said.
"I think we've still got work to do and a lot of it inevitably depends on where the competition is. Mercedes this year have done a great job, I think we are closing the gap, probably you can see that here this weekend."
The new contract is likely to mean a substantial pay rise for Bottas, even if Williams would not disclose any financial details, with the Finn already firmly on the radar of rival teams.
Massa, runner-up in the 2008 championship, brings with him important backing and has been reinvigorated after years at Ferrari largely in the shadow of world champions Michael Schumacher, Kimi Raikkonen and Fernando Alonso.
"They are an amazing team, fantastic people, it's like a family as well," he said on Sunday. "We are making this team stronger and stronger and bigger and bigger."
Reporting by Alan Baldwin, editing by Amlan Chakraborty