Lewis Hamilton maintained Mercedes' stranglehold on the top of the timesheet in F1's triple header as he led another one-two in second practice at the Austrian GP.
Since introducing their upgraded engine at the start of last week's French round, Mercedes have not been outpaced in any single track session - and, armed with a big chassis upgrade this weekend, Hamilton was ahead again in Practice Two from team-mate Valtteri Bottas, despite setting his best time on the slowest tyres available.
Hamilton's soft-tyre lap of 1:04.579 was nearly two tenths quicker than Bottas's best on the ultrasoft, a compound two steps faster. Hamilton did use the ultrasoft too but lapped fractionally slower than his impressive benchmark after a red-flag period.
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Sebastian Vettel was 0.236s back on his championship rival and, like Bottas, set his best lap on the ultrasofts. Daniel Ricciardo was the lead Red Bull in fourth and used the middle tyre, the supersoft.
Unusually, Red Bull appeared to be struggling more on their long runs with Max Verstappen, who was fifth, earlier reporting that his front tyres were struggling in the circuit's higher-speed corners.
But Ferrari, who have failed to show their hand on a Friday all season, showed far greater promise on the high-fuel runs with Vettel delivering the best lap-time average on the ultrasofts and Kimi Raikkonen on the supersofts.
"Mercedes look to have the advantage over a single lap but Ferrari look very strong on race simulations," concluded Sky F1 commentator David Croft.
As has become common place since the Austrian track returned to the calendar four years ago, drivers found the short but tight layout tricky to master - with the yellow 'baguette' kerbs on the outside of the final two sweeping corners in particular causing problems.
No more so than for Pierre Gasly, who ended up beached in the gravel after his suspension broke running over the kerbs as he ran wide over the penultimate corner.
"You've got to treat it like a barrier at Monaco," said Sky F1's Anthony Davidson. "You can't go out there - you have to change your approach."
The incident brought out the day's only red flag, although Gasly and his repaired Toro Rosso car were able to return to track for the closing stages and finished a promising ninth.
Hamilton, Vettel, Verstappen and sixth-fastest Raikkonen were among the many drivers to have brief off-course moments, along with Fernando Alonso, whose McLaren required a floor change after an early error.
The Spaniard, who spent much of the first half-an-hour in the garage, was only 19th, but team-mate Stoffel Vandoorne did provide under-pressure McLaren with some encouragement by making the top 10.
But it was Haas who topped the midfield at the end of a very strong opening day. Romain Grosjean, desperate for a first points finish of the year after a string of incidents, and Kevin Magnussen were seventh and eighth respectively.
The only moment of concern for Haas came late in the session when Magnussen was released from a pit stop with an incorrectly-fitted wheel. But, fortunately for the team, they were able to stop the Dane before he entered the fast lane of the pits, so should avoid a penalty from the stewards.