Lewis Hamilton team orders? All you need to know about Russia
There are so many questions going into the Russian Grand Prix.
Can the Mercedes drivers on the front row fend off Ferrari's Sebastian Vettel and prevent him slipstreaming past them from third place on the longest run to the first corner of the season?
Will Mercedes attempt to maximise Lewis Hamilton's championship prospects by employing team orders to ensure the Briton wins the race ahead of team-mate Valtteri Bottas, who beat him to pole?
How, for that matter, did Hamilton end up losing pole position to Bottas, after looking so dominant up to the final session of qualifying?
But almost certainly the most important question of all is, what on earth has happened to Ferrari's pace?
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Are Ferrari beginning to fall apart?
For much of this season, Ferrari have had the fastest car. But something has happened to them in Russia - and perhaps, in hindsight, at the preceding race in Singapore, too.
In Singapore, they looked to be the pace-setters until Hamilton's blistering pole lap in final qualifying. The view there was that Ferrari had simply messed up their qualifying session and failed to get their tyres up to the proper working temperature.
But Russia raises another possibility. Mercedes have utterly dominated the weekend, and Ferrari have been nowhere, a good half-second off throughout.
So, is Mercedes' advantage new this weekend - in which case, where has it come from? Or did the Mercedes step forward in Singapore - where ultimately Hamilton ended up with a similar margin - but it was disguised until qualifying?
Both teams arrived in Russia with major aerodynamic upgrades, focused on revised front wings and shapers at the front of the car.
So far, Mercedes' appears to have been the most effective.
Ferrari believe their car has problems in certain types of corners and say they are struggling particularly in Turns 16 and 17 towards the end of the lap, where the car is lacking rear grip.
They also believe Mercedes have made progress on tyre management - which tallies with the general perception that Ferrari are struggling to keep their tyres in good condition for an entire lap of Sochi.
Their lack of pace is a genuine concern - they expected to struggle in certain parts of the lap but not to be as far behind Mercedes as they are.
It will take more than this weekend to answer whether this reflects a general shift in the competitive order, but for Ferrari's title hopes it is bad news indeed. Vettel is 40 points behind Hamilton. If he does not make up ground on Sunday, it could be effectively all over bar the shouting.
A Mercedes quandary
Bottas took pole largely because Hamilton made errors in the middle sector on both his laps in the final part of qualifying.
"Valtteri has been driving well all year," Hamilton said. "I am happy for him. He did a great job and you can't get it perfect every time. I am only human. There is still a long way to go (in the race). The important thing is to try to convert that and make sure we hold those positions at least."
But "those positions" do not necessarily suit Mercedes' purposes. Or at least not in that order.
Hamilton's advantage over Vettel in the championship is substantial but Mercedes may feel the need to press home their advantage while they can.
If Bottas and Hamilton do get into the first corner with the Finn in the lead, the temptation to reverse their positions at some point in the race will undoubtedly be there.
Hamilton said he would "never" ask that of a team.
"We will be racing, but also as team-mates," he said. "So as to not do something silly towards each other. And then it is a train following whoever is in front and try to hold on to position."
But Bottas is aware of the possibility. "My approach to the race is definitely just trying to win," he said. "You can't have any other goal, starting from the pole. But of course we're here as a team. We're fighting for both championships.
"Obviously Lewis is leading the championship with a bit of a gap to Sebastian and a very big gap to me, so always need to keep those things in mind."
Mercedes F1 boss Toto Wolff is aware of the pros and cons.
Wolff said: "It was important for Valtteri to bounce back and regain some confidence but we are not in the part of the season where I particularly enjoy two Mercedes racing each there in the front. As much as I hate to say that as a race fan. You need to calculate a little bit more at this stage."
He said "none of us likes" team orders: "It is a very tricky decision and we will be discussing it with them tomorrow morning and we will come to a solution with the buy-in of everybody."
Can Vettel win the start?
Ferrari's pace may have been lacking so far this weekend, but a win is not necessarily out of the question.
The red cars are consistently fast starters - although Mercedes have improved in this area noticeably in recent races - and Vettel will think he has a decent chance of slipstreaming past the Mercedes into the braking zone at Turn Two.
Vettel said: "I was joking with Valtteri earlier that he should remember what happened last year where he was third, I was on pole. But you never know. It depends on the start. It depends on so many things. So, we will see.
"We will go racing and try to do, obviously, our best. It's been a bit of a tricky one for us. We didn't have the pace by quite a big gap, which is a surprise. But it is like this and we will fight as much as we can."
But do Ferrari have the pace to stay ahead even if Vettel does take the lead?
"I am quite positive," Vettel said. "I hope we can be a lot closer. If we are, we should have a good battle. If we are not, it will be bit less entertaining. If we can get ahead, we have a good chance but it is still a long race. If they are they much faster it will be difficult but we will try."
Have Renault pulled a blinder?
The second part of qualifying, in which drivers compete to make it into the top 10 shootout, turned into a bit of a farce when five of the 15 cars failed to take part, making the "knock-out" element of it rather redundant.
Red Bull drivers Daniel Ricciardo and Max Verstappen, and Toro Rosso's Pierre Gasly, were never going to take part - they have grid penalties for excessive engine usage and running after the first session made no sense.
But the other two non-runners were more intriguing.
Renault chose to keep Nico Hulkenberg and Carlos Sainz in the pits in an attempt to give themselves an advantage in the race - knowing the grid penalties for Ricciardo, Verstappen and Gasly would mean they start 11th and 12th.
The three other midfield teams in Q2 - Haas, Force India and Sauber - all chose to run. And so all their drivers made it into the top 10.
But in doing so, they are now committed to starting the race on the hyper-soft tyre, as the rules dictate that those in the top 10 have to start on the tyre with which they set their fastest time in Q2. Those outside the top 10 have free tyre choice.
The hyper-soft is fast over one lap, but quickly degrades, making it a poor race tyre - which is why Mercedes and Ferrari successfully attempted to make it through Q2 on the more durable ultra-soft.
Renault clearly learned from the last race in Singapore, where McLaren's Fernando Alonso, who qualified 11th, won the battle for best of the rest by starting on a harder tyre than those immediately ahead of him, including Hulkenberg, both Force Indias and a Haas.
The problem for Haas, Sauber and Force India is that their cars will be very slow in the first stint, and risk being leapfrogged during the pit-stop period as a result.
Esteban Ocon, who qualified his Force India sixth, said: "It will be really interesting to see how the hyper-softs perform in the race. We know there will be a lot of cars further back on the ultra-softs.
"Let's see how the strategies unfold, but I believe we can convert our strong performance into a good race result."
Hulkenberg called Renault's strategy "wise". But sporting director Alan Permane said that winning the midfield battle was far from a foregone conclusion.
"Our approach will be to gain places when those ahead of us have to pit early because of the short performance life of the hyper-soft tyres," he said. "This will benefit us early in the race. However, we still expect a very tight battle."
The comeback Kvyat
Off track, the weekend has been dominated by Red Bull's decision to re-employ Russian Daniil Kvyat at their junior team Toro Rosso next year.
This was an open secret well before it was announced on Saturday.
It's a fascinating story because the Russian's Red Bull contract was terminated at the end of 2017 - after he had been first demoted from the senior team to the junior one four races into the 2016 season, then dropped from Toro Rosso after Singapore in 2017, reinstated for a race when they found themselves short of a driver for the US Grand Prix and dropped again.
Kvyat was dropped because Red Bull's motorsport chief Helmut Marko felt he was never going to be put back into the main team - so why keep him?
But while Toro Rosso exists, someone has to drive the cars, and Marko felt it was worth giving him another chance.
Basically, Red Bull have found themselves in a pickle because their junior driver programme has run out of drivers.
Following Daniel Ricciardo's move to Renault for 2018, Pierre Gasly has been promoted to Red Bull. But there is no-one ready to step into the junior team, which exists solely to blood drivers for Red Bull.
The closest is Briton Dan Ticktum, who races in Formula Three, but he won't have enough FIA licence points for an F1 drive at the end of this season, and in any case Red Bull team boss Christian Horner says he is "not ready".
As Horner put it: "I don't think [Kvyat] had fully dealt with 2016. He's done that now, he's grown as a person, time for reflection, grown in experience, done a good job for Ferrari [as development driver] this year and it will be interesting to see what he can do in the Toro Rosso.
"He just has that little more experience now. He could be quick but was sometimes a little erratic. Hopefully you will see a much more rounded driver."
That still leaves another Toro Rosso seat to fill. Brendon Hartley, the incumbent, is not in Marko's good books and looks on rocky ground. The favourite is ex-Mercedes protege Pascal Wehrlein, who Marko says he has talked to, but is on "a long list".
Quite who else is on this list that is so long that Toro Rosso had to go back to a driver they sacked less than 12 months ago to fill one of their empty seats remains unclear.