Excelsior has presented Ágúst Orri Thorsteinsson, a 21-year-old Icelandic, as their new left winger. Thorsteinsson developed at the Breidablik youth academy and previously played for Malmö FF and Genoa. He arrives from Breidablik and has signed a contract in Rotterdam until mid-2029. He is regarded as the successor to Gyan de Regt, who departed for Holstein Kiel. Mark Ruijl, Excelsior's technical director, stated that de Regt's departure resulted in an increased need for a left winger. Ruijl also stated that Thorsteinsson fits the desired profile with his speed, depth, and direct style of play. Thorsteinsson stated that Excelsior showed significant interest in him from the beginning. He also mentioned that prior to his transfer, he spoke with several players active in the Netherlands, including former Excelsior player Elías Már Ómarsson. According to Thorsteinsson, these players were very positive about the club and its coaches and told him it was a perfect step for him at this time. In the Besta deild during the 2025/2026 season, Thorsteinsson made 47 appearances, scoring 7 goals and providing 5 assists. He has 10 caps and 1 goal for the Iceland U21 team. According to Transfermarkt, his current market value is €150k.