Lewis Hamilton was in outstanding form as he set the pace in first practice at the Abu Dhabi Grand Prix.
The McLaren driver was 0.333 seconds quicker than team-mate Jenson Button in second place. Sebastian Vettel's Red Bull was third, 0.765secs off the pace.
The German's title rival Fernando Alonso was fourth fastest as Ferrari tried out a number of new parts.
Red Bull's Mark Webber was fifth ahead of Michael Schumacher's Mercedes and Williams' Pastor Maldonado.
Schumacher's team-mate Nico Rosberg was eighth fastest, ahead of Williams reserve driver Valtteri Bottas and Lotus driver Kimi Raikkonen.
Five-time grand prix winner John Watson, acting as BBC 5 live summariser for the weekend, said: "McLaren will be very pleased with this afternoon's work. They have 0.3secs splitting their drivers and more importantly are 0.7secs ahead of Vettel. At this point, Hamilton and Button are in control."
Hamilton looked especially impressive. When he set his fastest lap of one minute 43.285 seconds he was 0.749secs faster than anyone else. Button later closed the gap to 0.463secs and then, with his last lap of the session, reduced it again with a time of 1:43.618.
Much of the interest in the session was in Ferrari's new parts, aimed at bringing them closer to Red Bull's pace and reviving Alonso's faltering title challenge.
The Spaniard has fallen to 13 points behind Vettel after a run of four consecutive wins for the Red Bull driver.
Alonso tried out a new front wing, a new rear wing and a new design of barge boards - the aerodynamic shapes between the front wheels and the sidepods.
BBC F1 technical analyst Gary Anderson said: "I've not seen any changes I'd get very excited about. Ferrari's new front wing is a nice bit of kit which will give them more consistent downforce but I'm not sure it will move them forward very much.
"With their new front wing assembly, Ferrari have gone to a six-element front wing, rather than the five there were before. If you count them all up it's 31 elements producing downforce.
"The idea is to get more consistency in the downforce. I'm not sure it will produce more downforce but it will be more consistent.
"I also think the concept of the endplate is a little critical - they are not doing what the other teams are doing, which is turning more air around the tyre.
"I think that comes from the problems they are having with their wind tunnel. It is too narrow, and turning more air around the front tyre effectively makes the car wider, which will be difficult to understand if the wind tunnel is too narrow."
Anderson added that it would be unwise to draw too many conclusions from the session as it was run in the middle of the day in Abu Dhabi, whereas qualifying and the race are held at dusk.
"Everybody has been trying to understand the cars a little better," Anderson said, "but I think this first session is very hard to read - qualifying and the race are held much later in the day. The second session later today will be more instructive."
At the back of the grid, Caterham were also trying a series of new parts in an attempt to wrest 10th place in the constructors' championship back from rivals Marussia before the end of the season. The position is valuable in terms of prize money and can mean millions of pounds.
Caterham performance director John Iley said: "A lot of people are working very hard. Very nice to see some more bits here, we have three races to go, hopefully we can show a bit of improved pace.
"We've modified the front wing, floor. We've brought some bits back to the car in terms of front brake duct corner and rear wing endplate we've been running previously and have some new bodywork and new exhaust bits and pieces as well. FP1 is about evaluating. Then we'll process those and go with them in FP2. We're hoping there's about 0.3secs in it."
Englishman Max Chilton did a creditable job in his first experience of driving at a grand prix weekend.
Replacing regular driver Charles Pic in first practice, Chilton was just under a second slower than his experienced German team-mate Timo Glock.