The Briton, looking for a hat-trick here, set the best time of 1min16.568 during the cloudy morning session; his team mate Valtteri Bottas was third and 0.555sec off Hamilton’s pace – but after a detour on the trackside gravel.
Sebastian Vettel, Leclerc’s team mate, was fourth on 1min17.172.
Hamilton is one point behind Bottas after four successive Mercedes 1-2 finishes so far in 2019 thanks to the Finn scoring a point for the fastest lap in the Australian season-opener.
Haas was strong with Romain Grosjean fifth and team mate Kevin Magnussen sixth ahead of Red Bull’s Max Verstappen – known for his 2016 triumph on this track in 2016 which made him, at 18-years-old, the youngest F1 winner.
British Williams rookie George Russell spun into the tyre wall in the closing seconds of the session.