Lewis Hamilton sent a message to team-mate Nico Rosberg and the rest of the field in the second practice for the Russian Grand Prix.
The championship leader was eight tenths clear of Kevin Magnussen, as the McLaren's continued their strong Friday pace, posting a 1:39.630 and was the only man to go sub 1:40 around the Sochi Autodrom.
Fernando Alonso produced an effort a little later than those around him and on the slightly grippier track was third ahead of Nico Rosberg as Valtteri Bottas and Jenson Button completed the top six.
Soft tyres prove much faster
After completing some initial longer runs on the medium Pirelli tyres, the usual afternoon swap to the option soft compound brought a big increase in pace.
Hamilton found approaching two seconds in time after putting the yellow-striped tyres on but not only is the option rubber much quicker it is also pretty durable with many drivers getting two if not three fast laps out of a set of tyres on a low fuel run.
The smooth, low grip nature of the Sochi track could mean that bringing the temperatures up to the right operating range could take more than just the one lap on the soft tyres so expect teams to be testing that theory in final practice and potentially carrying it through to qualifying.
McLaren and Toro Rosso surprise
In the morning it was all the Mercedes-powered teams who looked quicker than perhaps in recent races, but in the afternoon McLaren went so far as inserting themselves as outside bets for a podium on the Black Sea coast.
The good traction that helped Jenson Button so much in the wet at Suzuka, seems to be paying dividends again on the low grip surface and with the number of slow corners around the Olympic park circuit both Button and Kevin Magnussen are threatening Williams and Red Bull.
Also impressing are Toro Rosso who could be in with a shout of being the best Red Bull-backed team this weekend.
Russian Daniil Kvyat continued his pace from the morning and was again the fastest of the four cars in eighth just ahead of Sebastian Vettel and Jean-Eric Vergne.
Red Bull struggles
Indeed McLaren are not just threatening Red Bull but are way clear of them at least in practice as the team, who could see their four-year reign end as Constructors' champions this weekend, struggle to make any impact.
Sebastian Vettel was only ninth despite setting one of the later flying laps on the soft tyres while Daniel Ricciardo was only 13th.
And things got worse for the Australian as he caused a brief red flag right at the end after his RB10 grinded to a halt at the end of the log back straight.
The only positive for Red Bull is while their single lap pace is again much slower than we would expect, the long run times were more comparable to Williams and McLaren suggesting once again the team are concentrating on the race.
Further down, Force India again slipped down the order when single lap pace was being tested, despite having good race pace and being kind to the tyres, making the top 10 in qualifying has been their main problem and they could struggle to do so in Sochi with Nico Hulkenberg 12th and Sergio Perez 14th.
Sauber continue to languish near the bottom of the midfield as do Lotus who, fresh off announcing they will use Mercedes power units from 2015, were struggling for power and grip, particularly in the case of Romain Grosjean.
Finally at the back, Marcus Ericsson led the two slower teams for Caterham four tenths clear of the sole Marussia of Max Chilton with Kamui Kobayashi 21st and last.
Can Rosberg respond?
Back at the front, however, and the key question for most will be does Nico Rosberg have a response to Lewis Hamilton's impressive practice pace?
The German was on course to get much closer to Hamilton during a frenetic period where the McLaren's and Mercedes' swapped positions before Lewis ultimately stamped his authority, but a mistake at the penultimate corner cost him so we never got a true representation.
Other questions include whether McLaren can continue their mini revival and challenge Williams for the final place on the podium and also can Red Bull do the same thing?
And where will Ferrari be after Fernando Alonso finished third in the second practice session as team-mate Kimi Raikkonen struggled to 11th.
So many questions and still plenty of unknowns as a sombre yet increasingly intriguing F1 weekend awaits.
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