KIMI Raikkonen edged Lewis Hamilton for the fastest time in pre-season testing, a sign that Formula One could be regaining its competitive edge.
Raikkonen pushed his Ferrari through a flying lap of 1 minute, 20.960 seconds on day two of tests at the Circuit Barcelona-Catalunya.
While the Finn barely beat Hamilton's earlier effort by a scant 0.023 seconds, he did so using a slower type of tire made for greater durability over outright speed.
His good performance came after Ferrari's Sebastian Vettel had mustered the second-fastest time to Hamilton the previous day.
Lap times continue to drop as teams tweak cars that have been built since a profound rulebook overhaul by F1 to increase groundforce and grip, and thus boost speed.
Raikkonen's lap was almost two seconds faster than his own preseason-leading effort from last year's eight days of testing on the same track.
Hamilton, however, hinted that the Mercedes still has some power to unleash.
"My quick lap felt fast and tidy," Hamilton said.
"We've not really exploited the potential of the car, so it's all good foundation building at this stage."
With American team owner Gene Haas watching, Kevin Magnussen also impressed with his completed distance, racking up 118 laps to Raikkonen's 108.
Haas arrived in Spain fresh from relishing Kurt Busch winning the Daytona 500 for the NASCAR team he co-owns.
Mercedes surpassed Magnussen's total between Hamilton and Valtteri Bottas who shared time behind the wheel.
The pair combined for 168 laps in a second consecutive demonstration that the defending champions will be ready for the season-opener on March 26 in Melbourne.
Still, Ferrari's own fast and error-free start can give some hope to fans eager for more excitement, which has been limited to seeing Hamilton duel with the recently retired champion Nico Rosberg.
The teammates won 51 of the last 59 races en route to splitting up the last three titles.
Bottas repeated his strategy from Monday of getting in as many laps as possible in a race simulation, complete with pit stop practice for the Mercedes crew.
He tallied 102 laps in just four hours, and only had a slight bobble due to gusting winds.
"It wasn't anything serious," Bottas said.
"I lost the rear end with a gust of tail wind that was quite sudden. This is testing, you need to find the limits."
Max Verstappen had the day's third fastest lap, marking some progress for Red Bull following Daniel Ricciardo's opening-day snags due to a faulty sensor and battery.
McLaren, by contrast, took another step back after more trouble with its Honda motor.
Stoffel Vandoorne, who has replaced Jenson Button this season, spent more time waiting for his engineers to replace a power unit than driving.
That setback came after Fernando Alonso lost most of the opening session because of a problem with the oil system.
"It has been a difficult two days," Vandoorne said.
Testing continues through Thursday and then returns to the track near Barcelona from March 7-10.
Update your news preferences and get the latest news delivered to your inbox.