Aitor Karanka said he would rather not talk about the football after Boro's opening pre-season friendly win at York City was marred when debut man Alex Baptiste suffered a suspected broken leg before half-time.
The former Bolton defender, who joined Boro on Monday, was stretchered from the pitch after receiving medical attention for almost 10 minutes, and the severity of the injury left Karanka and his players visibly reeling.
"I don't like to speak about football after that," said Karanka. "I lost the game after what happened to Alex.
"I don't know exactly what has happened, but it looks like a serious injury, and he could be out for a long time. I think it is a complete break but we need to wait and see
"It's the worst way to start pre-season."
The game was settled by a Bradley Fewster goal 11 minutes from time, ensuring Boro started with a win.
"The attitude was good," added Karanka. "York are a good team and it was another good session."