Olympic 1,500m champion Faith Kipyegon, Winny Chebet and Edinah Jebitok booked semi-final slots after attaining the required time in their respective heats.
Impressive Kipyegon made light work of her rivals with a time of 4:01.40 to win the third heat-recording the best time overall in the heats too. Ugandan Winnie Nanyondo (4:02.24) and Australia's Linden Hall (4:02.27) were second and third respectively.
Kipyegon who won gold in Rio 2016 showpiece hopes for a second consecutive Olympic gold medal should she make it to the final. She's favoUrite for gold in the finals going by her past record.
She has bagged gold or silver in all major championships since 2014 when she was 20.
Placed third in the first heat, Chebet crossed the finish line clocking a time of 4:03.93. Gabrieha Debeus-Stafford and Laura Muir claimed the first two positions.
However, their respective time of 4:03.70 and 4:03.89 were slower than Kipyegon's. Chebet will hope to perform better than she did at the IAAF World Championships in Doha 2019 where she finished seventh with a record of 3:58.20.
Jebitok booked her place despite finishing 12th after a fall in her own heat won by Netherlands's Sifan Hassan who posted 4.05.17, with Australia's Jessica Hull finishing second ahead of American Purrier St. Pierre.
The 19-year-old world under-18 bronze medalist fell down after a tumble with Hassan from the Netherlands 400m adrift of her rivals on the final lap but was reinstated after Kenya protested the decision.
The semifinals set for Wednesday is set for two rounds with the finals slated two days later.
