It's moment of truth time for Nico Rosberg in 2013.
The German has been in Formula 1 for seven years without it really becoming clear just how good he is.
He produced one of the qualifying laps of the season to take pole in China, the foundation on which he built his maiden career win in Shanghai.
Rosberg's stats and facts
- Team: Mercedes
- Team-mate: Lewis Hamilton
- Previous teams: Williams
- Nationality: German
- Born: 27/06/1985, Wiesbaden
- Grand Prix debut: Bahrain 2006
But there were periods in the second half of the season when Michael Schumacher clearly had the measure of him - and this was a Schumacher, at 43, who was clearly not the driver he was.
But those question marks will all be erased this season,
for his partner at Mercedes is Lewis Hamilton,
whom former team-mate Jenson Button describes as the fastest driver he has ever seen.
How Rosberg measures up to the challenge will define the rest of his career.
Will he be able to compete, and therefore join the likes of Hamilton, Fernando Alonso, Sebastian Vettel and Button as a genuine ace?
Or will he be humbled, and be cast forever as a good number two, quick, solid, but lacking that final edge?
The world - and Rosberg himself - is about to find out.