Key questions before the Chinese GP

Ferrari suddenly threatening the recent dominance of Mercedes, Red Bull threatening to pick up its toys and leave the paddock altogether, Nico Rosberg threatening to wave the white flag early in the title fight against Mercedes teammate Lewis Hamilton, and McLaren Honda threatening - albeit a little less loudly - to make another major step forward in its difficult inaugural season.

DW takes a look at some of the burning questions in the pit lane in Shanghai ahead of the third round of the 2015 F1 season.

Is Vettel's prancing horse now in the running for the title?

The race in Malaysia was virtually an antidote to Melbourne. After Mercedes waltzed away with the season-opener, threatening another dominant campaign in 2015, Sebastian Vettel delivered his fairytale maiden Ferrari win. The German's emotional outpouring on the podium marked the start of a new era in the four-time champion's career, but did it really show that Ferrari can now regularly compete at the front?

Technical director and design ace James Allison - recently coaxed across from a career with the Enstone-based outfit currently badged as Lotus - sought to calm this speculation in the paddock in Shanghai.

"Of course, to finish at the front in a race is a great thing but it doesn't tell you much about what's going to happen in the future," Allison said. "We're up against a car, in Mercedes, and others too, that are strong competition. But Mercedes in particular, they have a bit more horsepower than us and a bit more downforce than us, and until we've closed those two gaps it's not realistic to talk about title challenges."

Prognosis: This season's Ferrari, the SF15-T, is the first to have Allison's fingerprints on it from conception through to usage. Its pace in Malaysia was close to, perhaps even equal to, Mercedes in race trim with heavy fuel on the Sunday. But Malaysia is the hottest race of the season, and a tough track on tires - all of which seemed to help the Italians. China will be significantly cooler, and just a little easier on the rubber. In these conditions, Mercedes showed signs of better "long-run" pace with heavy fuel on Friday practice, an ominous sign for the race. Expect a Mercedes on pole, and quite probably a Mercedes winner - the only real hope for Ferrari is that Mercedes' tire-wear problems aren't simply real, but are worse than generally believed.

The next races, in Bahrain and Spain, might prove happier climatic hunting grounds for the Scuderia.

Should Red Bull's F1 exit threats be taken seriously?

Dietrich Mateschitz has said it again. For now at least, the Austrian energy drink owner decided to pour some petrol - eschewing the water he had to hand - onto the rumors of a possible Red Bull exit from the sport.

"We'll only stay in Formula One if we have a competitive team, and we need a competitive power unit for that," Mateschitz told the Austrian Press Agency. "If we don't have one, we can race with the best car and the best drivers and still have no chance of competing for victory."

Red Bull's Renault engine is off the pace, and paddock politics make a change in engine supplier highly unlikely for what is effectively Renault's "works" team. But the RB11 is believed to have issues beyond the power units, such as braking problems, a theory that's born out by sister team Toro Rosso (also Renault-powered) outperforming it in Malaysia.

Prognosis: Paul Monaghan, chief engineer at Red Bull, might have the inside track on this one. He said ahead of qualifying that the team had corrected certain problems. RBR would see where it "sits in the pecking order" in Shanghai before commenting further, Monaghan said. Friday practice times - not always a reliable indicator - suggested that Red Bull might have made a sudden step forward. Daniel Ricciardo was third-fastest, though still a second adrift of Lewis Hamilton, in the second practice session. Suspiciously like Vettel and Ferrari in Malaysia two weeks ago, might another team be due a big boost just when it needs one?

Mateschitz could of course pull the F1 plug at any time (there's no way to argue that a fizzy drinks maker "needs" race cars to exist), but the series has become a key part of the company's rather inventive marketing approach. Perhaps the most likely Red Bull exit scenario would involve Renault leaving first; in that case, Red Bull might have no choice but to follow. Mercedes won't power the Milton Keynes-based team, probably fearing them too much as a rival. For the same reason, Ferrari seems an unlikely option, and all that leaves is the nascent Honda motor - with McLaren not a team renowned for its love of sharing either.

Is Nico Rosberg's off form an aberration, or permanent?

As Vettel shocked Mercedes, Nico Rosberg trundled home in third, again well adrift of Lewis Hamilton. But beyond that, the German has been cutting a glum figure of late - on the podium, on in-car radio, even in his regular post-race column in Germany's top-circulation paper, Bild.

Still seemingly struggling with changes to the rules on team radio, made after Hamilton complained that his teammate was getting too much help, Rosberg remains guilty of asking for information that teams can no longer offer drivers from the pits. "Can't help you with lines, Nico," race engineer Tony Ross said over the headset in qualifying, when Rosberg had asked for any tips on how to tackle the wet corners around the track. On the Sunday, too, Rosberg was chatty on his radio, but seemed to have no answer for Hamilton's pace in front, let alone Vettel's.

"Tell me about more about the race," he pleaded at one point in the closing laps - but there was really nothing for engineer Ross to say beyond that Rosberg was third, with no threat behind, but also showing no sign of catching the two in front.

After running Hamilton surprisingly close in 2014, his 2015 rematch with Hamilton is off to a non-start. Rosberg told readers of Bild after Malaysia: "My pace in the race wasn't good enough. Therefore I can hardly wait to do things better in China." He needs to.

Prognosis: China's home to happy memories for Rosberg; he won his first ever race (also Mercedes' first since their 2010 return as a full constructor) there in 2012. Then again, Hamilton won there, from pole, last season. It's a difficult, fiddly track to qualify on, getting a clean exit onto the back straight out of the long right-hander Turn 13 is crucial. Last season, Rosberg's superiority in qualifying was a key to his challenging Hamilton, who won more races - so Saturday would be the ideal time to start his recovery.

How big a step have McLaren Honda taken this time?

Let's leave what seems like the more outrageous assertion for last. It might not immediately seem fair to say that McLaren Honda have taken any "steps" this season so far. With no points and just one race finish to its name, the team could scarcely seem any further back.

What's more, neither car made it to the finish in Malaysia, meaning that the team's "progress" was not that easy to identify. But at the season-opener in Melbourne, Jenson Button simply had orders to potter home in the MP4-30, whose new Honda engine had been dialed down in terms of horsepower to improve reliability. In Malaysia, with the dials turned up, suddenly both McLaren cars were running with the pack, until they conked out. On Friday in China, in a development that might have seemed unthinkable back in Melbourne, both McLarens logged times that would put them mid-pack. Have McLaren really come from the very back of the grid to the midfield in just one month?

Prognosis: If the MP4-30 isn't ready to keep up with the midfield and battle for points on Sunday, all the indications are that, eventually, it will be - and sooner than many expected. Honda is a year behind the other three engine makers and still in serious trouble, but it's unlocking potential in its power unit at a rate of knots.

The ever-jovial veteran Jenson Button seems happy even mired in this 2015 adversity - perhaps he knows a little more than most at this early stage. Button has told both British F1 broadcasters, the BBC and Sky, that McLaren's plan was to write off the early races as a development phase, so that they can fight at the front later this season. These claims look less daft with every passing session.