Valtteri Bottas completed a sweep of Portuguese Grand Prix practice on Saturday with Mercedes team mate and Formula One championship leader Lewis Hamilton second fastest.
The Finn, quickest in both Friday`s sessions at the Algarve circuit near the southern city of Portimao, lapped with a best effort of one minute 16.654 seconds.
Hamilton, the six-time world champion who can take an outright record 92nd career win on Sunday after equalling Michael Schumacher`s milestone, was 0.026 slower on a sunny but cool morning.
Both drivers made errors, with Hamilton tracking through the gravel at one point.
Red Bull`s Max Verstappen was third fastest, 0.158 off the pace, with AlphaTauri`s Pierre Gasly — whose car caught fire on Friday — fourth on the timesheets.
The session was ended a minute early after a drain cover came loose at the exit of turn 14 as Sebastian Vettel`s Ferrari went over it.
Mercedes have qualified on pole for every race so far this season and look set to extend that run to 12 in a row later on Saturday.
The team can also clinch a record seventh successive constructors` title on Sunday if results go their way, although Red Bull`s form is likely to keep them waiting at least another week.
Hamilton is 69 points clear of Bottas after 11 races.