The Super Eagles are scheduled to face Poland in Warsaw on Wednesday before travelling to Leiria for a high-profile clash against Portugal on June 10 as preparations continue for future competitive assignments.
Both Osimhen and Lookman were included in Chelle's original squad when the list was announced two weeks ago. However, the two key attackers have now been withdrawn from the team for separate reasons.
Speaking to the Super Eagles media team, Chelle explained that Osimhen has been excused from the fixtures to focus on resolving uncertainty surrounding his club future.
"We miss two players because Victor Osimhen maybe he is about to change club so I prefer he stays at home because if he plays and is not at 100 percent is not good," the Malian tactician said.
Chelle also disclosed that Lookman has been granted permission to miss the matches following a request from his club.
"For Lookman he is very tired and Atletico ask us to excuse him."
The absence of two of Nigeria's most influential attacking players comes on the back of the team's recent success at the Unity Cup in London.
The Super Eagles lifted the trophy on Saturday after an emphatic 3-0 victory over the Jamaica national football team in the final, continuing their positive run under Chelle.
With Osimhen and Lookman unavailable, attention will now turn to the remaining members of the squad, who will have an opportunity to stake their claim for regular places as Nigeria continue preparations for crucial fixtures ahead. The friendlies against Poland and Portugal are expected to provide Chelle with another chance to assess his options and further shape the team for the challenges ahead.