The Serie A giants were thrashed 6–1 away at the Aspmyra Stadion in Norway in an UEFA Europa Conference League group stage clash.
Roma are now second in Group C table with six points after three games. The return clash against Bodø/Glimt will be played in Rome on Thursday, November 4.
Interestingly enough, the shocking defeat was the first time that a team led by Mourinho conceded six goals in one game (on what was the 1,008th game of his managerial career).
After the final whistle, the Portuguese said: "I decided to play with this line-up, so the responsibility is mine. I did it with good intentions, I decided to rest players. We lost against a team that showed more quality. It's that simple."