The Oxford-Cambridge boat race is one of the most famous events in the world and this year a woman will umpire the men's race for the first time.
Sarah Winckless, who is a former Cambridge University student, will make sure everyone is playing by the rules at the race on 29 March.
She said "it's a real honour and responsibility" to be the first female umpire.
It's not the first time she has umpired, having done it for the women's race in 2017 and umpired the reserve men's race in 2016.
It's a competition that takes place between two of the oldest universities in the world, Oxford and Cambridge.
The yearly event takes place on the River Thames in London over a 4.2 mile course.
The first ever Oxford-Cambridge Boat Race took place in Henley-on-Thames in 1829 when a Cambridge student challenged an Oxford student to a race but it didn't become a regular fixture until 1856!
The first women's race was in 1927, but it was not until 1964 that it became a regular thing.
Cambridge has won 84 men's races to Oxford's 80, while Cambridge's women have won 44 to Oxford women's 30.
Being in charge of a major event like the Boat Race is no easy task.
The umpire has to make sure neither crew goes outside of their own racing line and sticks to the rules (there are 10).
The rules of the race state the crews must keep to their stations (the Middlesex or Surrey sides of the river) unless they have a lead of "clear water" when, if they wish, they can use the opposite station.
But they have to row through the centre arches of two bridges where they often come really close to each other.
Sarah is well qualified to be an umpire as she's competed in three Olympic Games and won a bronze medal in Athens in 2004 with doubles partner Elise Laverick.
She was also awarded an MBE in the Queen's Birthday Honours in 2015 for services to sport and young people.