The German coach, who is 38 years old, was extremely angry after the opposing team's captain, José Luis Gayà, committed a violent tackle on Anthony Elanga a few meters from the touchline.
Newcastle's new coach rushed to the assistant referee demanding a red card, which Gayà later received, while the players of both teams clashed briefly.
Swedish winger Elanga, one of Newcastle's standout players, was carried off on a stretcher in the 39th minute, concluding a truly disastrous start for the German coach with his new club.
Despite Newcastle's 2-1 victory, Jaissle was furious about the tackle Elanga suffered.
The Sun newspaper revealed that Elanga suffered a bruise to his leg, but it is not as serious as his coach initially feared.
Article
Newcastle star injury provokes Yaisle's anger
Matthias Jaissle, the new technical director of Newcastle United, entered into a quarrel with the assistant referee, then a scuffle occurred between his players and those of his opponent Valencia, during a friendly match between them in preparation for the new season.