Mercedes duo Valtteri Bottas and Hamilton were almost half a second clear of Sebastian Vettel in qualifying in the desert - the biggest margin of the year.
The world champions have taken pole for all three races in 2017 so far, but Hamilton claims that it will not be so easy in the race proper.
He told Sky Sports News: "I think the Ferraris are very quick on race trim so hopefully it will be very close. [On Saturday] we obviously had a bit of a margin to the Ferraris, but generally in race trim they seem a bit quicker."
Pole position for the Bahrain GP has been taken by Bottas - the first of his career.