According to Globo.com, Olympiacos formalized their interest and made proposals to Fluminense for Martinelli, with these offers occurring from the beginning of the year to the present. The maximum amount presented by one of the clubs was 14 million euros. All proposals happened before Martinelli's call-up to the Brazil national team. Fluminense currently considers the player 'non-negotiable' due to his importance to the team and the decisive stage of the season. The club expects that new proposals could be made in the next transfer window, particularly following the call-up.

According to the Turkish outlet 'Fotospor', Fluminense's Martinelli remains a target for Olympiacos ahead of the upcoming summer. In the previous January transfer window, reports from Brazil indicated a 12 million euro offer from Olympiacos was rejected.

Olympiacos submitted an offer of approximately €12,000,000 for 24-year-old Brazilian defensive midfielder Mateus Martinelli, which was rejected by Fluminense. Besiktas, West Ham, and teams from the Gulf also made similar offers that were all rejected by the Brazilian club. Fluminense values the player at a minimum of €20,000,000. Martinelli's current contract is valid until 2027, and there is a desire from his club to extend it until 2030. According to Transfermarkt, his current market value is €14.00m. For the 2025/2026 season, Martinelli has made 3 appearances and provided 1 assist in the Campeonato Carioca, and has made 1 appearance in Série A.