Mikel described Thursday's clash with the Panthers as the most important fixture in Nigeria's qualification series.
He warned that complacency could prove costly, advising the players to take their opponents seriously and show the professionalism required to reach the next stage.
"The first game is the most important game. Gabon is the most important game," said Mikel, via The Obi One Podcast Channel.
"Don't underestimate Gabon, please don't because if we do that then we are in trouble."
"Go into that game and play like this is the last game you will ever play in your life, win that game and then we can think about either Cameroon or someone else."
"The mistake we are going to make is to think it's just Gabon, then we are done completely."
The Super Eagles began their preparations on Monday afternoon at the Rive Hotel training ground in Rabat, Morocco, where they have been fine-tuning tactics and fitness ahead of the decisive encounter.
Mikel's message serves as both encouragement and caution, reminding the team of the stakes involved.
A victory over Gabon would see Nigeria advance to the final round of the playoffs, where they could face either DR Congo or Cameroon for a place at the 2026 FIFA World Cup.
With expectations high and qualification within reach, Mikel stressed the need for unity and discipline, noting that only complete focus would deliver success.
