It's a funny coincidence that several of the greatest drivers of recent times had their birthdays in the early months of the year - Lewis Hamilton and Michael Schumacher are just four days apart - but rather handily that gives us a chance to compare how their careers stood at this stage of the seasons in which they turned 23 years old.
In 1992, Schumacher had just finished his first full season at Benetton. He'd recently won his first grand prix at Spa, but he still had a lot of learning to do, and the first title was two years away, achieved when he was 25.
In 1983, Ayrton Senna had just won the British Formula 3 Championship with West Surrey Racing, and was about to enter his first Formula One season with Toleman, a midfield team with whom he could learn without having too much pressure on his shoulders. His first grand prix win was a little over 18 months away, but he wouldn't win a championship until he was 28.