Lewis Hamilton edged Sebastian Vettel in first practice at the Bahrain Grand Prix on Friday.
Hamilton clocked 1 minute, 33.572 seconds in his McLaren around the 3.4-mile Bahrain International Circuit, 0.305 seconds quicker than two-time defending champion Vettel for Red Bull.
Force India driver Paul Di Resta was a surprising third followed by last week's Chinese Grand Prix winner, Nico Rosberg of Mercedes.
Hamilton's teammate Jenson Button was fifth while Vettel's teammate Mark Webber was eighth.
Just an hour before second practice, Force India announced it would not take part in the practice because of safety concerns. The announcement also came amid reports that anti-government protests will start about 30 minutes after practice ends.
On Thursday, there were sporadic clashes, including riot police firing tear gas and stun grenades at protesters chanting anti-F1 slogans. Downtown shops also shuttered early amid the tightened security.
On Friday, Ferrari continued to struggle with Fernando Alonso finishing 13th and Felipe Massa 15th.
Most drivers quickly adjusted to the dry and dusty circuit, which is holding an F1 race for the first time in two years. The 2011 race was canceled because of anti-government protests that that have left nearly 50 dead.
Several drivers went off the track at the tricky turn 10. Timo Glock of Marussia spun out on the first corner but the German quickly recovered. He placed 22nd of the 24 cars.
Force India deputy team principal Robert Fernley said the decision to skip the second practice was made following the first practice session and a day after two team members left the Gulf nation in the wake of a team vehicle being briefly delayed because of a firebomb.
The sport's governing body, the FIA, released a statement confirming that Force India would miss the second practice after neither of its two drivers took the track. It said both drivers would miss the practice due to "logistical reasons" which will force the team to "run a rescheduled program for the rest of the weekend."
Security was tight ahead of the session following days of sometimes violent anti-government protests.
There were checkpoints on the roads leading to the track. Additional security troops have been deployed around the circuit and across the capital, Manama. There were no signs of protests at the circuit early Friday.
Supporters of the Shiite opposition plan to rally later Friday against the F1 race. It is backed by the ruling Sunni dynasty but is opposed by demonstrators who contend it rewards a regime that continues to detain political prisoners and commit human rights abuses.