Yuki Tsunoda has conceded his rookie F1 campaign in 2021 was the "hardest" of his motorsport career after struggling for form across the year.
Tsunoda arrived in F1 with a bang, ending pre-season testing second fastest only to eventual champion Max Verstappen and scoring points in his debut race.
Both events took place in Bahrain, a venue at which Tsunoda had grown accustomed to when racing in feeder series F2.
When the season moved to Imola, the Japanese driver's struggles began with numerous errors creeping in across the weekend including a heavy crash in qualifying and a spin in the race.
The mistakes kept coming through the year, although positive drives did begin to emerge at the end of the season.
Speaking in an interview including GPFans in December, Tsunoda said: “It was a big learning year and also the biggest and hardest topic I had in my racing career in terms of how I had to improve.
"If you go up, step up to Formula 1, most of the topics are almost solved but there are some things, topics that you have to improve, which are the topics I never think about."
Across the year, Tsunoda was comfortably outscored by team-mate Pierre Gasly, with the Frenchman ending the year 78 points better off.
The gulf in performance is further highlighted with Tsunoda registering points at just seven races, a total that matches the number Gasly failed to score at.
Tsunoda added: “It was really hard to solve this answer and also improve myself so, definitely was the biggest year for in terms of learning."