Hull were comfortably beaten by Bundesliga side Eintracht Frankfurt in a 120-minute pre-season friendly in Germany.
Goals in each half from Jonathan Burkardt and Love Arrhov inflicted the Tigers' first loss of pre-season.
New signings Konstantinos Tzolakis and Jens Hjerto-Dahl made their first appearances for Hull in the club's penultimate friendly, which consisted of two hour-long halves.
Sergej Jakirovic's side will conclude pre-season next Saturday against French Ligue 1 outfit Nice before their Premier league return.