Nico Rosberg outpaced Mercedes team-mate and defending world champion Lewis Hamilton to clock the fastest time in Friday's floodlit second free practice session for Sunday's Bahrain Grand Prix.
The 29-year-old German clocked a best lap in 1min 34.647sec to finish up one-tenth of a second clear of the Briton at the Sakhir Circuit on which he seeks pole position for the third consecutive year.
Hamilton, who won last year's race with some thrilling moves in a dramatic contest, ended up under investigation by the race stewards for 'failing to leave the pit lane correctly', a misdemeanour that is unlikely to upset his confident form this year.
"I just followed Kimi (Raikkonen) when he went round a car that was stopped there," Hamilton explained afterwards. "I don't really know what happened, but I thought it was ok to do that."
Finn Raikkonen of Ferrari was third fastest ahead of his team-mate German Sebastian Vettel after the four-time champion's session was curtailed by a collision that broke his car's front wing when he was clipped by Mexican Sergio Perez of Force India.
"I had a failure, a brake failure, and then Perez took my wing off," said Vettel. "Unbelievable."
The stewards announced an investigation into the incident.
Behind the Ferraris, Finn Valtteri Bottas was fifth for Williams ahead of Australian Daniel Ricciardo of Red Bull, Venezuelan Pastor Maldonado of Lotus, Brazilian Felipe Nasr of Sauber, Russian Daniil Kvyat in the second Red Bull and Brazilian Felipe Massa in the second Williams.
Mercedes AMG Petronas German driver Nico Rosberg prepares to take part in the 2nd practice session ahead of the Formula One Bahrain Grand Prix in the Bahraini capital Manama. (AFP PHOTO)
For Rosberg, his success was a much-needed boost as he bids to end Hamilton's supremacy and cut his lead with his first victory of the year.
He said he had been studying recordings of last year's race to learn ways in which he can improve on a track that he likes and believes is suit to his driving style.
"Do I think I can gain an advantage over Lewis here? Yes, I do," he said. "But I also thought that at the last two races. I'm here to make it happen.
"I've looked at the videos again from last year because I need to improve in battle. There are things I could have done differently last year to win that race so I'm looking at that and I hope to follow it up well."
Rosberg denied that he felt any more pressure on him to recover following Hamilton's good start to the season with two wins in three races and a 17-point lead in the title race.
"It was already important [to turn things around] in Malaysia and that was two races ago," said Rosberg. "It doesn't change. Every race is important. He's 17 points ahead. That's a fact.
"So, I need to try to get points back as soon as possible - it's not more important here or whatever."
Hamilton said he had enjoyed the session, adding that "the car feels good and I am very happy here."
Raikkonen was later given an official reprimand for a slight infringement of the strict pit lane rules during the second free practice session.
Raikkonen and Hamilton both crossed a white line to make their way out to the track behind a Sauber that had just emerged from the pits.
Both were called before the stewards, who carried out an investigation into the incident and decided to give Raikkonen a reprimand. No further action will follow against him or Hamilton.