World championship leader Nico Rosberg set the pace in opening practice for the Russian Grand Prix but it was Red Bull who stole the show after they trialled their canopy.
The proposed head protection device, which is being considered as an alternative to the so-called halo concept, was fixed to Daniel Ricciardo's car.
More protection needed
Unlike the halo - a concept first devised by Lewis Hamilton's Mercedes team and subsequently tested by Ferrari in pre-season - the canopy, also dubbed the aeroscreen, has no central pillar but two pillars on the side, with a windscreen acting as a shield.
SIGN UP NOW
Want to become a GMS writer? Sign up now and submit a 250-word test article: http://gms.to/haveyoursay4
Article continues below
Following a number of high-profile incidents in recent seasons, including the fatalities of Henry Surtees - the son of former world champion John Surtees - in a Formula Two race at Brands Hatch in 2009 and Briton's Justin Wilson at an IndyCar event last year, which were both caused by flying debris, motor racing's governing body the FIA is determined to introduce improved cockpit protection for 2017.
Ricciardo completed just one scheduled lap with the canopy attached to his Red Bull in the opening moments of the 90-minute session before returning to his garage.
Article continues below
Rosberg in control
And given the thirst for improved driver head safety it now seems inevitable that the canopy or the halo will be approved by Formula One's governing body next season.
Back on track, and Rosberg, winner of the last six grands prix, posted a best lap of one minute and 38.127 seconds at Sochi's Olympic Park to lead the way ahead of Hamilton.
The Briton, already 36 points adrift of his Mercedes team-mate, was nearly a quarter of a second slower than Rosberg with the Ferrari duo of Sebastian Vettel and Kimi Raikkonen third and fourth in the order.
Hamilton, Vettel and Jenson Button, 11th for McLaren, were among a number of drivers to spin in the opening session ahead of the Russian race which has been moved from its spot at the back end of the calendar to May 1 to coincide with a national holiday.
After taking the canopy off his Red Bull, Ricciardo placed sixth, splitting the Williams pair of Felipe Massa and Valtteri Bottas. Russian Daniil Kvyat was eighth for Red Bull in front of his home fans, while his compatriot Sergey Sirotkin, on his first outing for Renault, was nearly one second quicker than Jolyon Palmer in the sister car.
What do you think of Red Bull's new canopy? Have your say in the comments.