BELGRADE, Serbia — At the appointed hour, the man picked up his phone, sat down on the couch in his hotel, and dialed the number.

“Yes, hello, I’m calling you on behalf of Fare,” he said, dropping the name of a network based in London that fights discrimination in world soccer. “Just to inform you, I will be the matchday observer tonight in Belgrade. We have done some research. Of course, we all know it’s a high-risk match ….”

The match in question, set to begin a few hours later, was a Europa League contest last Thursday between Partizan Belgrade of Serbia and Skenderbeu of Albania. The person on the other line was the UEFA delegate assigned to supervise proceedings at the stadium. And the so-called risks? They were abundant, including the potential for displays of racism, political extremism and homophobia. Two weeks earlier, the same teams had met in Albania, and UEFA, which governs soccer in Europe, later had cited a report documenting “racist behavior” and “illicit chants” by Skenderbeu fans when it fined the club $70,000.

Inside the hotel last week, hours before the rematch in Serbia, the man from Fare finished the call and prepared to head to Partizan Stadium. He would work that night as an anonymous observer, one of the dozens trained by Fare to notice everything from flags and banners to chants and slogans that can merit punishment for violating UEFA’s disciplinary code. Since 2013, Fare has monitored hundreds of games each year in Europe, quietly dispatching its monitors, with UEFA’s blessing, to both club and international matches where incidents are likely.