Haller scored the winning goal for his country against Nigeria in the final of the African Cup of Nations, crowning them with the title after the goal he scored against the Democratic Republic of the Congo enabled his country to reach the final match, after almost being eliminated from the round of 16.

In June 2023, Alier, 28 years old, who plays for the German club Russia Dortmund, was diagnosed with testicular cancer. He underwent two surgeries and underwent about 5 months of chemotherapy.

 In his first match with his team, Borussia Dortmund, after recovering from the disease in January 2023; Haller appeared with great level and high morale.

Doctors discovered that Haller was seriously ill during a training camp in which he participated a few weeks after joining Dortmund for $33 million from Ajax Amsterdam, for whom he scored 34 goals, including 21 in the league and 11 in the Champions League.

The Nigerian Kanu also played an influential role with the Nigerian national team and led it on several occasions after he underwent serious heart surgery in 1999 and was then playing for the English club Arsenal.