Ademola Lookman, a former winner of the African footballer of the year award, like Osimhen, opened the scoring after 20 minutes in Fes on Monday and helped set up the other three goals on the night.
Osimhen had started the game without wearing his trademark mask, but restored the face covering before netting Nigeria’s second goal on 25 minutes. He then scored again just after half-time before Akor Adams sealed the win.
It is the biggest winning margin in an AFCON knockout tie since Egypt hammered Algeria 4-0 in the semifinals at the 2010 tournament in Angola.
Determined to make up for their failure to qualify for the World Cup, the Super Eagles march on to a last-eight tie on Saturday in Marrakesh against either Algeria or the Democratic Republic of the Congo (DRC).
The teams clash in the last 16 on Tuesday, and a victory in the game for the DRC would offer Nigeria a chance to avenge their defeat on penalties against the Leopards in a World Cup qualifying playoff in November.
Mozambique appeared in the knockout phase of an AFCON for the first time after advancing as one of the best third-placed sides in the group stage.
They were no match for a Nigerian team that was much-changed from their final group game, when coach Eric Chelle offered a chance to several fringe players for a 3-1 victory against Uganda.
Atalanta forward Lookman, who scored in the 3-2 win over Tunisia in the second group match, was among those brought back into the lineup, and Africa’s best player in 2024 gave his team the lead as the midway point in the first half approached.
Alex Iwobi’s through ball released Adams on the left side of the box, and his cutback was converted first-time by Lookman.
The 28-year-old then turned provider, with his cross from the left in the 25th minute being helped on by Adams, for Osimhen to poke the ball in from close range.
The Galatasaray striker emerged unscathed soon after that, despite going into a challenge with Witi, which saw the Mozambique player knee Osimhen in the stomach.
Lookman’s low ball across the face of goal from the left was finished off by Osimhen to make it 3-0 in the 47th minute and end any prospect of a Mozambique comeback.
The 2023 African player of the year had gone seven AFCON matches without scoring before netting against Tunisia in the group stage. He now has three to his name at the tournament in Morocco.
Lookman was not finished for the night as he supplied Adams inside the box with a quarter of an hour remaining, and the Sevilla forward rifled a shot high into the net.
Earlier in the day, Egypt needed extra time to overcome Benin 3-1 to book their place in the next round, where either Ivory Coast or Burkina Faso await.
