Mourinho was seen in the stands at the Tivoli-Neu stadium in Innsbruck, Austria.
The manager’s appearance comes as Manchester United are linked with a move for Austria and West Ham star Marko Arnautovic.
It is not known if Mourinho was at the game specifically to watch the player in action but Arnautovic did start the friendly.
And the manager may well have been impressed by what he saw on Wednesday night.
Arnautovic was one of Austria’s key men as they beat the World Cup hosts 1-0.
He caused the Russian defence problems throughout and set up Alessandro Schopf for the only goal.
He also forced a fine save out of Igor Akinfeev in the first half.
Arnautovic was eventually subbed off for Deni Alar with six minutes remaining.
Russia are preparing for the World Cup this summer, while Austria failed to qualify.
The Austrians are therefore beginning their preparations for Euro 2020.
Arnautovic, 29, has today emerged as a target of Manchester United, who are keen to get deals done before the World Cup starts.
West Ham appear resigned to losing their winger if a suitable offer comes in.
Arnautovic, who only joined the Hammers from Stoke last year, scored 11 goals for the Hammers this season as they avoided relegation to the Championship.
He cost the east London club £24m and West Ham would likely want an increase on that fee to let him depart for Manchester United.