Mixed conditions during final practice set the tone for the day ahead, with relatively limited running throughout the field. Lewis set the fastest time of the morning, Valtteri the fifth fastest.
While it remained dry through the first two qualifying sessions, intermittent showers in the pole position shootout made life tricky for the drivers out on track and the engineers on the pit wall too.
Fortunately, the team got it just right, with the cars sent out just at the right moment for Lewis and Valtteri to ace their laps before the rain intensified.
Lewis went on to claim his 80th Formula One pole position - his eighth of the 2018 season and second at the Suzuka International Racing Circuit.
Valtteri will start tomorrow's race from P2, completing a front row lockout for the team with his best-ever starting position in Japan.
Today's result marks the 175th front row place for Mercedes-AMG Petronas Motorsport in Formula One