South Korea's Seo Young-Jae has inked a three-year deal with Hamburger SV that will see him stay with the club until 2018.
The 20-year-old, who was plying his trade with Seoul-based club Hanyang University, impressed coach Bruno Labbadia during a trial and was snapped up prior to the conclusion of the transfer window.
The left-back, who has represented South Korea at Under-19 and Under-21 level, will start join the Hamburg Under-23 side.
Two players departed Hamburg on Tuesday, with midfielder Petr Jiracek having returned to his native Czech Republic after signing a four-year deal with Sparta Prague.
Fellow midfielder Kerem Demirbay joined second-division Fortuna Dusseldorf on a season-long loan.