Bahrain Grand Prix qualifying: Maiden pole for Bottas, no power for Alonso
Valtteri Bottas took pole for Mercedes, while Fernando Alonso's McLaren suffered power problems - again.
Renault had a good start to the evening - Nico Hulkenberg progressed in sixth, with Jolyon Palmer just behind in eighth.
Meanwhile, Carlos Sainz had a terrible end to the session, parking up before he completed his final flying lap, complaining of no power.
"Sorry for that," came the response from the pit wall - after he'd recorded the quickest first-sector time as well.
Kimi Raikkonen lost a bit of his car on his last attempt to record a quick time - but he was still third-quickest overall.
Mercedes' Lewis Hamilton topped the charts, having spent most of free practice pointing out how daft it is to try out cars and strategy for a night race during the daytime.
OUT: Carlos Sainz (Toro Rosso), Stoffel Vandoorne (McLaren), Sergio Perez (Force India), Marcus Ericsson (Sauber), Kevin Magnussen (Haas)
Fernando Alonso, down the way for McLaren, was nowhere to be seen - and was spotted with four minutes to go with his gear partially removed.
He explained afterwards that he had suffered a power-unit problem - something he's quite familiar with at this point.
Elsewhere, Haas's Romain Grosjean sang happy birthday to himself, two days prematurely, as he came in ninth.
At the top of the leaderboard, the Renaults had another utter stormer - Hulkenberg in fifth and Palmer in tenth. The Mercedes of Hamilton and Valtteri Bottas were split by 0.02 of a second, with the Ferraris of Sebastian Vettel and Kimi Raikkonen tucked behind them.
OUT: Daniil Kvyat (Toro Rosso), Lance Stroll (Williams), Pascal Wehrlein (Sauber), Esteban Ocon (Force India), Fernando Alonso (McLaren)
Bottas worked incredibly hard to put pressure on Hamilton, recording the quickest-ever lap time in Bahrain - but the Brit responded well and hit back, 0.05 seconds quicker immediately, taking the advantage in the final sector.
But finally the Finn's persistence paid off - Hamilton's middle sector went horribly wrong, handing pole position to his team-mate for the first time ever.
GRID: Valtteri Bottas (Mercedes), Lewis Hamilton (Mercedes), Sebastian Vettel (Ferrari), Daniel Ricciardo (Red Bull), Kimi Raikkonen (Ferrari), Max Verstappen (Red Bull), Nico Hulkenberg (Renault), Felipe Massa (Williams), Romain Grosjean (Haas), Jolyon Palmer (Renault).
QUALIFYING IN SUMMARY
It's a Mercedes one-two on the front row - but Bottas leads the Silver Arrows this time. Vettel was disappointed with his Q3 performance, and will feel he has something to prove tomorrow. Renault had an exceptional time of it - but can they replicate it when it counts?
Perhaps not a shock, but Ricciardo quietly working to go quicker than the blood and thunder of Verstappen was neatly done - but then, he's never been outqualified by a team-mate in Bahrain.
ONE TO WATCH
Kimi Raikkonen is never ruffled, exactly, but like Vettel he was unhappy with his display in qualifying - watch him in the race.
Hamilton - Bottas - Vettel