Amusan ran a time of 12.48 seconds to come first in heat
number five, with Megan Tapper coming second in a time of 12.51 seconds.
Michelle Jenneke of Australia ran a time of 12.71 seconds to
come third in the race, while Natalia Christofi came fourth in a time of 12.90
seconds.
Amusan will attempt to reach the final of the tournament on
Wednesday.
Amusan is the current World, Commonwealth and African
champion in the 100m hurdles, as well as the meet record holder in those three
competitions.
Amusan became the first ever Nigerian world champion and
world record holder in an athletics event when she won the 2022 World
Championships 100 m hurdles gold medal, setting the current world record of
12.12 seconds (+0.9m/s) in the semi-final, followed up by a 12.06 seconds
(+2.5m/s) in the final.
She won back-to-back Commonwealth and African titles in 2018
and 2022 in the 100m hurdles and is also a two-time African Games champion in
the event.
She is also the current Diamond league champion in the 100
metres hurdles having won the final in 12.29 seconds (-0.3m/s) winning back to
back titles in 2022 and 2023.
Amusan's presence at the global showpiece was a surprise,
with her suspension lifted just two days before the meet began.
The Athletics Integrity Unit (AIU) provisionally suspended
the Nigerian last month due to three whereabouts failures within a 12-month
period, but the decision was overturned by the AIU's disciplinary tribunal
panel.
Her announcement in Tuesday's heat received a mix of cheers
with a smattering of boos.
The details of her case will be published on the AIU's
website as early as Wednesday, chair David Howman told reporters. The AIU have
30 days to decide whether or not to appeal to the Court of Arbitration for
Sport (CAS).
"We have some concern that it might set a precedent
which will be difficult for future cases," Howman said. "So the job
we will undertake is to get an independent review of the decision, to determine
whether we should consider appealing and then as a board we have to decide
whether we will take that step."
The semi-finals are on Wednesday.