"....a veritable master class of Bludger work"
-- description of shots taken by Aliko Okoye and Mercy Ojukwu, match report by Ginny Weasley for the Daily Prophet (Pm)
Ojukwu was a member of the Nigerian team at the 2014 Quidditch World Cup tournament. She and the other Nigerian Chaser, Aliko Okoye, were "ferocious" against Fiji in their first match, winning by 400 points to 160 (Pm).
Prior to the tournament, the Nigeria National Team was considered to be one of the favourites to win in 2014. In spite of an artistic display of ability - by both sets of Beaters - they lost their quarter-final match against the Japanese National Team (270-100), due to the disintegration of their Seeker's Thunderbolt VII during the match (Pm).
Hitting a Bludger in an artistic, creative and precise manner
Other canon notes and references
Mercy means "compassion, forgiveness, pity" and derives from the Latin "merces" (payment, reward) (Babyname Wizard).
Two famous Nigerian actors are named Mercy: Mercy Aigbe Gentry and Mercy Johnson Okojie.
Odumegwu Ojukwu, a Nigerian general, was the President of Biafra from May 1967 to January 1970 (Wikipedia).
From the Web
Screenshots of the Daily Prophet's coverage of the 2014 Quidditch World Cup: http://imgur.com/a/AXutv