Nottingham Forest have completed the signing of Ivory Coast centre-back Ousmane Diomande from Sporting, adding a 22-year-old defender with Champions League and title-winning experience to Oliver Glasner's squad.
Multiple outlets reported that Diomande has committed to a four-year contract, with Forest holding an option to extend the agreement by another season. The exact fee has not been officially disclosed. Reports placed it between £34m and £34.3m, while one account described the €40m deal as a fixed payment following prolonged negotiations.
A major investment in Forest's defence
Diomande arrives after making 132 senior appearances for Sporting in all competitions. His spell in Lisbon brought two Portuguese league titles, while he also featured prominently during the club's run to the Champions League quarter-finals last season.
Forest's chief football officer George Syrianos highlighted the defender's high-level experience and success at a relatively early stage of his career. The club's assessment is that Diomande has the physical authority and competitive background to settle quickly into the Premier League.
The signing continues a summer rebuild under Glasner. Reports indicated that the Forest head coach had identified Diomande as a priority and had previously attempted to bring him to Crystal Palace during his time in charge there. That history suggests the move is not simply a late-window opportunity, but a recruitment decision closely connected to the manager's preferred defensive profile.
How Diomande could fit under Glasner
Glasner is expected to use a three-man central defence, a system in which Diomande's arrival has clear implications. According to reports, he could line up alongside Nikola Milenkovic and Murillo, giving Forest a combination of differing but complementary attributes across the back line.
Diomande has generally operated as a centre-back with the mobility to defend larger spaces, an important requirement in a back three when the outside defenders are asked to cover wide channels. His experience of Sporting's possession-based football should also be relevant when Forest look to build attacks from deep rather than relying solely on direct play.
The transfer may offer Glasner greater flexibility rather than automatically displacing one established defender. A three-centre-back setup needs depth because injuries, suspensions and tactical adjustments can quickly change the balance of the unit. Diomande's addition could allow Forest to shift personnel depending on the opponent, while preserving a stronger level of cover across a long campaign.
At 22, he also represents a longer-term acquisition rather than a short-term solution. Forest are paying a substantial reported fee for a player who has already accumulated extensive club experience but still has scope to develop in a more demanding league.
International and European pedigree
Diomande has earned 15 caps for Ivory Coast, according to the reports, and was part of the country's squad at the 2026 World Cup. He made one group-stage appearance, in the victory over Curaçao.
His club record is the more substantial indicator of his readiness. After beginning his senior journey in Ivory Coast and spending time with FC Midtjylland in Denmark, he joined Sporting in January 2023 and rapidly became an important player. His starts in both legs of Sporting's Champions League quarter-final against Arsenal were among the highest-profile matches of his career.
That exposure does not remove the adjustment involved in moving to England. The Premier League's tempo, frequency of transitions and aerial demands present a different test from Portuguese football. Yet Forest have recruited a defender who has already dealt with knockout European competition, title pressure and international football.
A statement of intent, with work still to do
The reported fee makes Diomande one of Forest's most significant acquisitions of the window. It follows the arrival of Austria midfielder Xaver Schlager on a free transfer, while the wider squad has also seen notable change.
For Forest, the value of the deal will rest on how quickly Diomande can establish partnerships with Milenkovic, Murillo and the rest of Glasner's defensive structure. His résumé points to a player accustomed to competing near the top of domestic competition; the next challenge is translating those strengths into Forest's new system.
Diomande said he was pleased to join a club with Forest's history and expressed confidence that the group could make progress this season. The transfer gives Glasner a defender he has admired for some time, and gives Forest an increasingly well-equipped group for a tactical reset at the back.