MONZA, ITALY (REUTERS) - Finland's Valtteri Bottas and Brazilian Felipe Massa will race for Williams again next season in an unchanged line-up, the Formula One team said on Sunday.

"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 in a statement.

"This announcement gives us excellent stability for 2015, but of course we are very much focusing our attention on maximising the full potential of the FW36 in the remaining seven races of this season."

Massa joined Williams from Ferrari at the end of last year while Bottas has been with the team for five years and been one of the standout drivers of a season that has seen Williams back among the leaders after a woeful 2013.

The former champions are fourth overall in the championship ahead of Sunday's Italian Grand Prix with 150 points after scoring just five last year.