Diaw finished top of his group after first defeating Adam Hmam of Tunisia - the host nation - 9-11, 11-9, 11-5, 11-9, 11-7, before getting the better of Nigeria's Quadri Aruna 11-7, 11-8, 11-8, 6-11, 11-13, 11-7.

A Commonwealth Games silver medallist in 2018, Aruna also made the Olympic quarter-finals in 2016.

However, Aruna's chances of reaching Tokyo 2020 hang in the balance after a hip injury forced him to withdraw from his match against Hmam, seeing Hmam finish second in the group and qualify for this summer's Olympics.

Aruna will either need to be successful at the International Table Tenis Federation World Singles Qualification Tournament in Doha in late May, or hope his world ranking is good enough to secure qualification.

In the other men's group, fellow Nigerian Olajide Omotayo did qualify alongside Algeria's Larbi Bouriah, although the latter was pushed all the way. 

He needed seven games to defeat Tunisia’s Kerem Ben Yahia 7-11, 6-11, 11-9, 11-5, 10-12, 11-5, 11-9.

Two more Nigerians qualified in the women's competition - Offiong Edem and Olufunke Oshonaike.

Edem was the top seed and Oshonaike number three - both remained unbeaten and Oshonaike will be making her seventh Olympic appearance.

Cameroon’s Sarah Hanffou came second behind Oshonaike in one group to also book at place at the Games, while Tunisian Fadwa Garci was the other runner-up and is Tokyo-bound too.

The tournament continues tomorrow with the mixed doubles competition, where there is one Olympic place on offer.