The Brazilian veteran told MMA Fighting he had an infection that gave him kidney stones. He's currently taking antibiotics and is expected to be cleared to train again in a month, hoping for a return to the UFC cage around November or December.
The Fight Night card will take place at the Royal Arena in Copenhagen, Denmark, on Sept. 28.
Alves (23-14) fought twice this year, scoring a close decision win over Max Griffin in February but then losing a decision to Laureano Staropoli in May. “Pitbull”, a former welterweight title contender, was victorious in only two of his last seven UFC bouts.
Nelson (17-4-1) is looking to get back on track after dropping a split decision to Leon Edwards in March, four months after a brutal second-round finish over Alex Oliveira. The Iceland-native is 4-4 since having his 13-fight winning streak snapped in 2014.