LAGOS, Aug. 3 (Xinhua) -- South Africa's Caster Semenya on Friday reasserted her dominance of the women's 400m at the ongoing African Senior Athletics Championshipsin in Nigeria's southern city of Asaba.

Semenya won the race in 49.96 seconds, while Christine Botlogetwe of Botswana came second with 51.19.

Nigeria's Yinka Ajayi who featured at the 2018 Commonwealth Games at Gold Coast in Australia placed third with 51.34.

Sierra Leone's Margaret Barriere finished fourth with a time of 52.06, while Patience Okon-George came fifth with a time of 52.34.

Semenya who emerged on the world track scene in 2009 has won two Olympic titles - in 2012 and 2016.

She has also won gold medals in three International Association of Athletics Federations (IAAF) World Championships - 2009, 2011 and 2017.

Semenya won both the 800m and 1500m titles at the 2018 Commonwealth Games.

The 21st African championships which began on Wednesday will end on Sunday.