Nigeria were expected to be comfortable winners in their opening match against minnows Burundi, competing in this tournament for the first time, but that was not the case as they were pushed all the way.
The three-time African champions took 77 minutes to find a way through, with Odion Ighalo's composed finish proving the difference between the sides at the Alexandria Stadium.
Gernot Rohr admitted after the match that his side were made to "suffer" by Burundi, and next up is what should be an even tougher game against a Guinea side ranked 63 places better off than the Super Eagles' previous opponents in the FIFA rankings.
Nigeria did ultimately get the job done, however, and the Ighalo-inspired victory made it five wins in a row in the Africa Cup of Nations - their longest-ever streak in the competition.
The West African nation, who have not conceded more than one goal in any of those five wins, are now expected to get the job done against Guinea on Wednesday, taking off the pressure for their final group match against unknown quantity Madagascar.
Having lost just one of their last 10 matches over the last year - 1-0 to Senegal in their final warm-up match - Rohr's side are showing why they are many peoples' favourites to go all the way this year.
After failing to qualify for the last two tournaments, Nigeria's current crop now have a chance to redeem themselves.
Recent form in AFCON: W
Recent form (all competitions): DWWDLW
Guinea came away from their Group B opener against Madagascar with a point that boss Paul Put described as "disappointing" after throwing away a one-goal lead at the Alexandria Stadium.
Sory Kaba put the National Elephants in front with 34 minutes played, only for Anicet Abel to profit from some poor defending to head home a corner - Madagascar's first AFCON goal - before Carolus Andria made it 2-1.
That forced Put to throw on Naby Keita, and the Liverpool midfielder's introduction made a difference as Guinea created more chances and levelled up via Francois Kamano from the penalty spot to claim a point.
Keita's fitness was a big talking point heading into the biennial showpiece, having missed the final stages of Liverpool's campaign with a groin problem that he has only just recovered from, though he now looks ready to play a full part.
Put has called on his players to cut out the sloppy errors if they are to have any chance of claiming a positive result against Nigeria, knowing that defeat to the Super Eagles and victory for Madagascar over Burundi will see his side drop to third.
Guinea are now winless in their last six games in the Africa Cup of Nations, drawing four of those. Their last success in the competition came back in 2012 against Botswana.
Five of Guinea's last 10 goals in the competition have been scored following set-piece situations, including a couple of penalties, and if they are to have any hope of making it to the latter stages they need to start creating from open play.
Recent form in AFCON: D
Recent form (all competitions): DDDLLD
Ighalo top scored in qualifying but he was named among the subs against Burundi, though his goal should see him reclaim his place up top.
Despite being criticised for a lack of goals, meanwhile, Arsenal winger Alex Iwobi is expected to retain his place out wide.
It has also emerged that Shehu Abdullahi's campaign may have come to an early end because of a hamstring issue that will be monitored.
As for Guinea, Put will surely have to take a risk on the fitness of key player Keita in what is a huge match for his side.
Mohamed Yattara was brought on for Kaba late on in the National Elephants' opener and is pushing for inclusion here.
Nigeria possible starting lineup:
Akpeyi; Awaziem, Troost-Ekong, Omeruo, Aina; Ndidi, Etebo; Chukwueze, Mikel, Iwobi; Ighalo
Guinea possible starting lineup:
Aly Keita; Dyrestam, Jeanvier, Falette, Sylla; Diawara; Traore, Cisse, Naby Keita, Kamano; Kaba
Head To Head
Nigeria and Guinea have only met once before at the Africa Cup of Nations - a 1-1 group-stage draw in March 1976.
The Super Eagles are winless in their last four meetings with Guinea in all competitions after losing none of the previous eight.
We say: Nigeria 1-0 Guinea
Ighalo's goal in a tight game against Burundi really was massive for the Super Eagles. They are now under less pressure and should have enough to overcome Guinea, who are facing a seventh game without a win in the continental competition for the first time.
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