Installation laps have been completed, all 18 cars are back in the garage.
Worth remembering in the opening half hour the drivers have an additional set of prime (medium) tyres to encourage early running. Those have to be handed back on the half-hour mark.
With his team-mate's car in the garage, Magnussen is the first car to venture out on track.
Very interesting-looking aero sensor on the side of Magnussen's car, too. Looks like he's about to go and try to blow up the Death Star.
Magnussen returns straight to the garage after one lap, so there are still no times on the board.
@RohanMehta: Tough to do though! Would need a lot of options. I'll think of a poll for later on in the session.
@mfbull: "Ok Lewis, it's Hammer Time. It'll be just like Beggar's Canyon back home."
Verstappen ventures out of the pits and stops at a line so he can do a practice start. He shudders a couple of times and then heads out on his merry way.
Button is out of the car so his weekend keeps getting worse.
Verstappen crosses the line to go P1, the first time of the weekend a 1:19.999.
@RCC: Indeed, that's what McLaren's aero sensor would have been doing. Biggest aero sensor I've seen on a car for a few races.
Verstappen dips a wheel on the grass at Turn 1 and then has an almighty wobble at the end of Turn 6.
Sutil and Kvyat cross but can't topple Verstappen's first benchmark.
Sutil runs deep at Ferradura, where there's one of those popular tarmac run-off areas.
@Sekhar: Nope, no sign of rain yet.
@RCC: Magnussen's probably tuning in to hear what they're saying about Button.
@marspit: Nor can I. Remember, however much gains teams make next year, Mercedes could just make gains of its own and just move the goalposts further forward. It's a long process ahead for Ferrari.
@Siddhesh: We try to keep things interesting.
Alonso now goes top with a 1:16.921.
Kvyat splits the Ferrari's, with Raikkonen five tenths off Alonso's initial benchmark.
Only Button, Gutierrez and Magnussen in the pit lane.