Formula 1 has amended the rules regarding rejoining the circuit at Turn 2 after drivers had difficulty with the imposed system on Friday.
At Turn 2, a 'slalom' rejoin system was implemented for the opening day of practice, which forced drivers to weave around three different posts before coming back onto the circuit.
However, many drivers had difficulties in doing so, as they entered the run-off area at a point that was too late to go back and go around the first sign.
The system has been revised and a new rule is now in place. Drivers only need to use the new system if they pass "completely to the left of the first orange kerb element prior to the apex", as was the case on Friday.
However this time, the drivers must rejoin must circuit "by driving to the left of the white blocks and remaining to the left of the orange block in the run-off".
Another overnight change has seen Pirelli decrease the minimum front tyre pressures from 23 to 22 psi.
Bahrain International Circuit - Winter testing