Last year, the German reeled off nine straight victories, matching the record set by Alberto Ascari in 1952 and '53, to capture his fourth consecutive world championship with ease.
The switch to six-cylinder turbo engines and the introduction of new fuel-saving regulations in the offseason, however, have brought a sudden halt to Vettel's stunning dominance of the sport. In the first three races of this season, he's managed a single podium finish — third place in Malaysia.
He's also been relegated to second-best driver on his own team at times, finishing behind Red Bull debutante Daniel Ricciardo three times in four qualifying races, including Saturday's session at the Chinese Grand Prix, in which the Australian was second and the German third.
His recent struggles have perhaps been so surprising that Vettel was asked how it felt to be back in the post-race news conference in Shanghai, reserved for the top three finishers in qualifying.
"I missed probably one race, so it's not a disaster," he said.
Mercedes driver Lewis Hamilton, a two-time winner this season and the pole-sitter for Sunday's race, jokingly came to his rival's defense: "He's been in quite a few times over the years, so..."
Vettel's troubles can be traced back to the preseason testing of Red Bull's newly redesigned cars, which caused the team a series of technical problems. The German then struggled mightily in the opening race of the season in Australia, slumping to 12th in qualifying and retiring after five laps in the race with engine problems.
Ricciardo, meanwhile, has thrived with his new team. He captured his first podium in Australia with a second-place finish, though the result was later stripped after he was found to have breached the sport's new fuel regulations.
He'll now have another chance Sunday, starting next to Hamilton on the front row in Shanghai.
Vettel doesn't sound too worried about his new teammate's strong performance — or his own problems — so far.
"Maybe I'm struggling a little bit more, but at the end of the day, we have the same car — there's nothing between the cars — so if he manages to beat me, then he beats me on the circuit, fair and square," he said.
"Of course, that's not to my liking, but equally I know that I have to do a little bit better."