The club released an update on the fitness of a number of players before the showdown at the Emirates Stadium and confirmed he will not be involved.
"In full training following transfer from Brazilian pre-season," said the Gunners of their new defender. "Aiming to be available for selection for Olympiacos."
While there was disappointing news on Mari's condition, Arsenal confirmed that Sead Kolasinac, Reiss Nelson and Bukayo Saka are all available.
Another January signing, Cedric Soares, and summer acquisition Kieran Tierney will miss the match with the Magpies, although Arsenal have said both are seeking to be fit before the end of the month.
Arsenal are in action in the UEFA Europa League on Thursday in their first leg against Greek giants Olympiacos, with a place in the last 16 of the competition at stake.
Mari will be disappointed not to be involved on Sunday, as will the supporters who have been keen to see him in action since his loan switch from Brazilian outfit Flamengo. The centre-back was the first signing sealed by new manager Mikel Arteta.
The Arsenal boss has spoken about what he expects the Spaniard to bring to the team:
The defender only moved to Flamengo last year, although he was quickly able to establish himself in the side. He was a crucial figure in a successful campaign for the Brazilian outfit, as they were crowned domestic champions and Copa Libertadores winners.
WhoScored.com noted that he's strong in the air, although he can be a little rash in the challenge:
It will be fascinating to see how Mari fares in the Premier League. The 26-year-old was on Manchester City's books between 2016 and 2019, although he never made a senior appearance for the club after spending three years out on loan at different sides.
Arsenal will hope he can get up to speed quickly and offer some defensive cover, with Calum Chambers set to sit out the season with an injury. The Gunners have struggled at the back this term and go into the showdown with Newcastle down in a disappointing 10th place in the Premier League.