The Norwegian low-carbohydrate team Strømsgodset have won the league cup for the first time since 1970. Kenn Hallstensen, responsible for the team’s diet, makes sure they eat a restricted amount of carbohydrate (Google translated from Norwegian).
The advantages of a low-carb diet in sports are a lower fat mass (desirable in most sports) and a higher fat-burning capacity coupled with higher endurance (especially useful when matches last longer than 1 hour). Reports state that Strømsgodset steamrolled their opponents during the final 45 minutes.
A very strict low-carbohydrate diet may however reduce explosive strength, which is why a more liberal low-carb diet may often be preferable for optimal performance.
Norwegian newspaper Dagbladet: Strømsgodset Played Their Way to Championship Gold After a Dream Game Against FKH (again, Google translated from Norwegian).