Sebastian Vettel's dominant run continued as Red Bull's world champion set the pace in practice for the Chinese Grand Prix.
McLaren were again his closest rivals as Lewis Hamilton was 0.166 seconds behind with team-mate Jenson Button third ahead of both Mercedes drivers.
Ferrari's Fernando Alonso was 14th in second practice following a problem with the hydraulics on his car.
Scot Paul di Resta missed the second session with a fuel-pressure problem.
It was a frustrating day for Renault's Nick Heidfeld, who crashed twice.
The Formula 1 field had returned to action just five days after 16 of the 24 cars crossed the line in Malaysia.
Senior staff at Ferrari, McLaren and Williams returned to their factories to check on the progress of their upgrades.
But after Vettel had a clean sweep in Australia and Malaysia, Red Bull boss Christian Horner and chief technical officer Adrian Newey stayed out in Malaysia.
"It's been a great start particularly for Sebastian," Horner told BBC Radio 5 Live during first practice. "We are coming to China off the back of those results and we will try and build on them."
Vettel showed no signs of losing momentum as he out-paced team-mate Mark Webber to top the timings in the morning session and the afternoon followed a similar pattern.
Red Bull spent the early part of the afternoon focusing on tyre performance over longer stints, with Vettel reporting his tyres were starting to degrade on only his eighth lap.
But there was no stopping Vettel setting a fastest time of one minute 37.688secs when the German ventured out on the softer tyres.
Vettel said: "We had a good day, but it's only Friday and so it's early in the race weekend.
"We found a good rhythm and we're happy with the car. There's still a lot to do and I think it will be tight in qualifying and the race, so we'll look where we can improve."
Webber finished the day 1.639secs adrift of his team-mate but there were no obvious problems for the Australian and the Red Bull team-mates may have been running different strategies.
"I don't think we saw Vettel's true potential there," said 5 live analyst Anthony Davidson. "It was a dominant performance.
"Who's to say McLaren didn't have another second of fuel on board as well? It's not over yet but all signs point to Red Bull."
McLaren arrived in Shanghai eager to close the gap on the world champions and used practice to try out the new exhaust system and floor that they abandoned in Malaysia as well as a new front wing.
Hamilton and Button took turns to set the pace before being overhauled by rivals Red Bull in both sessions.
The morning was not without its problems for the British pairing. There were two excursions and a lock-up in the pits for Hamilton, who had a brakes issue, while Button was affected by a Kers failure.
McLaren team boss Martin Whitmarsh said it was too early to know if the updates had helped the English team claw back any of Red Bull's advantage over a single lap.
A more comfortable afternoon session saw Hamilton close to within 0.166secs of Vettel with Button 0.247secs adrift.
But Hamilton said his "gut feeling" was that the new parts were not an improvement.
Asked if McLaren were closer to Red Bull's pace this weekend, Button said: "No, not at all. I don't think we are at the moment. If we sort our balance out we'll be closer.
"The car is still a good car to drive but we didn't improve the balance of the car and we will look at why the changes we made didn't give us the improvement."
Di Resta, who finished 15th in the morning session, was unable to get out in the afternoon because of a fuel pressure problem, so for the third race in a row the Scot only took part in a single spell of Friday practice.
Heidfeld, who drove to third in Malaysia, had both his sessions cut short after he lost control of his Renault twice and ploughed into the barriers in bizarrely similar circumstances.
"It was just a mistake," Heidfeld told BBC Sport after the first incident.
Davidson commented: "It's not a good day for Heidfeld. He's got the speed but he's just making those silly mistakes."
Vitaly Petrov had a straightforward day in the other Renault and finished 1.117secs off Vettel's leading time.
Ferrari brought a front wing and new front brake ducts from their Maranello headquarters to Shanghai but Alonso warned he was expecting another "difficult weekend".
The Spaniard was out-paced in the morning by his team-mate Felipe Massa and a hydraulics problem limited his running in the afternoon.
Alonso said: "When the car is good, the qualifying will be good and the race will be even better, so it is what we have to do.
"We have to find some time in the car, some improvements, and then the qualifying and the race pace will come together.
"That is the main priority for us. Improve the car as quickly as possible, get new parts every race and hopefully they work good enough.
"We know some other teams will bring new parts as well, we just need to bring something more than them."
Brazilian Massa set the sixth fastest time - 0.819secs behind Vettel - on a three-lap run on the soft tyre.
Ferrari technical director Aldo Costa said: "We did with Fernando a lot of aero tests, not a lot of real running to test the new pieces. And concentrated with Felipe on tyres.
"Of course we have to catch up as we are quite behind and at home people are motivated to progress and we were discussing as usual development programmes and which parts we can bring to the races.
"We are pushing to catch up and come back to the performance that we like to have."