The Super Eagles striker scored the only goal as Napoli beat Mourinho’s men 1-0 on Sunday night.
A run of 10 consecutive victories has now made the Partenopei Europe’s most in-form team.
They had scored 32 goals in those games, a rich average of more than three goals per game but against Roma, Luciano Spalletti hit a button quite unexpectedly.
The Napoli manager picked Osimhen over Giacomo Raspadori to start the Serie A clash
Fed with a route-one ball from Mateo Politano, Osimhen wrestled off the holding Chris Smalling before delivering a stunner from the most impossible of angles.
“We have to be more decisive upfront, what lodges into the statistics are the shots on goal.
“Then I also look at the half opportunities, those that you have to transform into opportunities as Osimhen did,” Mourinho told DAZN after the game.