How it unfolded
The 1983 championship swung by a handful of points all season between the 22-year-old Freddie Spencer on the Honda NS500 and Kenny Roberts, riding his final year on the Yamaha. At Anderstorp the two once again broke clear of the field alone, and the race was decided in the chicane on the final lap. Spencer braked extremely deep on the inside, sending both machines off the track and onto the grass; he got back onto the circuit first and took the win outright. Roberts finished second and publicly criticised Spencer's move afterward as disrespectful to a rival. The season finished with Spencer on 144 points and Roberts on 142, a two-point margin. Spencer became the youngest 500cc champion in history, a record that stood until Marc Marquez arrived in 2013. Roberts retired at the end of that season.
Why it still matters
This was the moment it was confirmed that the block pass, taking the road a rival needs before they can, is legitimate at the highest level. Over the following 40 years it became the standard overtaking move in MotoGP, and it also opened the ongoing debate over where fair racing ends and dangerous riding begins.