The race ended early due to an accident involving Jules Bianchi.
Williams objectives on Friday was aero evaluations, set-up and tyre work.
Williams Martini Racing has maintained its third place in the Constructors’ Championship.
The team have been working overnight to improve the performance of the Williams Mercedes FW36.
Objectives: Aero evaluations, set-up and tyre work
The English team will fight to keep the third position in the constructors' championship.
Valtteri Bottas finished in fourth position in today’s Italian Grand Prix.
Williams Martini Racing is pleased to announce that it will be retaining the services of Felipe Massa and Valtteri Bottas as the teams’ Race Drivers for the 2015 FIA Formula One World Championship season.
Valtteri Bottas qualified third and Felipe Massa fourth.
Valtteri Bottas: "ObjecWe tested the new aero package today which works well."
Valtteri Bottas finished third and Felipe Massa thirteenth in the Belgian Grand Prix.
The changeable wet conditions were not ideal for the FW36 and traffic on their out laps in Q3 hindered the driver’s ability to get the full performance from the car.
One of the classic Formula One venues, Spa-Francorchamps is loved and respected in equal measure by the drivers...
Ferrari could learn from Williams' recovery from the doldrums of the British team's past few seasons.
Eleven races down, eight more to go in the 2014 Formula One season.
Mika Hakkinen has acknowledged rumours linking his protege Valtteri Bottas with McLaren.
Felipe Massa finished fifth and Valtteri Bottas eighth.
Valtteri Bottas challenged Sebastian Vettel for second, while Felipe Massa struggled with traffic in Q3.
Felipe Massa: "We have run both cars with the new rear wing and it's very positive so far."
Felipe Massa's race unfortunately ended early after he was involved in a first corner incident.
Niki Lauda has criticised Williams, in the wake of female driver Susie Wolff's Friday morning appearances at Silverstone and Hockenheim.
Both Williams drivers stayed towards the top of the field throughout qualifying eventually being beaten by only Nico Rosberg.