Faith Kipyegon is the 2021 Diamond League 1500m champion.
The Olympic champion defeated perennial rival Sifan Hassan in the final 100m stretch to emerge top with a time of 3:58.33.
The Dutchwoman clocked 3:58:55 to finish second in another heated race that brought fans in the Letzigrund Stadium in Zurich up on their feet.
Hassan beat Kipyegon by more than two seconds to win her 2019 world title.
But in July at the 2021 Monaco Diamond League meet, Kipyegon returned the favour by defeating Hassan by two and a half seconds in a national-record 3:51.07, becoming the fourth-fastest of all time at the distance.