Nigeria beat Tanzania by 35 runs, but they needed their final wicket partnership to rescue them from a massive hole. Yunusu Issa and Salimini Saidi took three wickets apiece to reduce the Super Eagles to 89 for nine.
It was a parlous situation, but Segun Ogundipe (62) and Igeanchukwu Uboh (23 not out) saved some serious blushes for the West Africans.
They took the total to 169, before Ogundipe was last man out, having given his team something to defend.
In reply, Tanzania became the second team to suffer at the hands of young Peter Aho, who took 4/37.
That ripped the heart out of the chase, and Isaac Danladi cleaned up the tail with three for 8, as Nigeria prevailed. Only Gokul Das, with 62, stuck it out, with Tanzania eventually all out for 134.
In the second match, Sierra Leone survived a Frederico Carava hurricane of wickets, to post a nervy 167 all out against Mozambique.
Carava recorded career-best figures of 7/33, which included three wickets in his second over, to see Sierra Leone tumble to 31/5 after eight overs.
It needed calm heads, and those were provided by Osman Sankoh (51) and Aruna Kainessie (40), who steered them to calmer waters. 167 was a lot more than they might have expected at 31/5 and then 122/8.
The Mozambican chase was stifled by Sierra Leone's young guns, as 13 year-old Haroun Kamara and 14 year-old James Tommy shared six wickets, conceding just 47 runs in their combined 20 overs.
That saw Mozambique bowled out for 96, and sealed what looked like a comfortable victory on paper.
In reality, of course, Sierra Leone knew that they were pushed hard - for the first time in the competition - and their lower-order stood up to the challenge.
The tournament concludes tomorrow with Mozambique taking on Tanzania for the final qualifying sport in Division1. Nigeria play Sierra Leone for bragging rights at Senwes Park.
Scores in brief
Nigeria vs Tanzania
Nigeria 169 all out (S Ogundipe 62, I Uboh 23 not out, S Saidi 3/27)
Tanzania 134 all out ( G Das 62, P Aho 4/37, I Danladi 3/8)
Nigeria won by 35 runs
Mozambique vs Sierra Leone
Sierra Leone 167 all out (O Sankoh 51, A Kainessie 40, F Carava 7/33)
Mozambique 96 all out (J Bulele 18, J Tommy 3/15, H Kamara 3/32)
Sierra Leone won by 71 runs
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