It was unclear as to why Byers left the rink, but Team GB had said before the competition that they would only use their permitted substitute if aplayer was injured or ill.
Sully Muntari came on as a second-half substitute, seemingly confirming Mourinho's belief that the player had reduced energy levels as a result of fasting for Ramadan.
The goal was tough on the home team, who would have levelled almost instantly but for a superb block by McCarthy, who smothered a shot from Owls substitute - and former Palace player - Tom Soares.
Laszlo handed 17-year-old Scott Robinson, who became the youngest player to feature in the SPL when he made asubstitute appearance two seasons ago, his full debut while there was also a rare start for strike partner Jamie Mole.
The Frankfurt-born player was given his international debut by Guus Hiddink and was mainly used as asubstitute at the 2002 World Cup while still a student, where his only start was in the semi-final against Germany.