In the second of the day's split sessions, he clocked the second fastest time in the first-out, even-numbered group.
The RSF-backed Prema driver was also second on the timesheet on second fastest laps which determine the race three grid.
Rookie George Russell topped the session on both counts, shading Dennis by 0.019s and 0.085s respectively. But the Carlin driver had to cede provisional double pole to Signature's Alexander Albon who set the fastest and second fastest times in the follow-on, even-numbered session.
The Lotus F1 junior pipped Van Amersfoort's race one pole winner Charles Leclerc on fastest times by 0.196s and Carlin's Antonio Giovinazzi on second fastest times by 0.078s to claim both poles.
Dennis - who qualified 10th for tomorrow's weekend opener - will start both races from fourth on the grid.