A challenge with Kyle Walker-Peters in the final ten minutes of Sunday’s stalemate forced the Argentine winger off in stoppage time despite his introduction only 15 minutes earlier.
However, the 18-year-old was partly taken off for Fred to bolster United’s defence late on in the game, after towering striker Paul Onuachu came off the bench for Southampton.
Ten Hag has described Garnacho’s injury as “not too bad” but said the substitution was also for tactical reasons, as he also brought Harry Maguire on to secure the point.
“He was limping a little bit after a bad tackle,” confirmed the manager.
“So in the end I thought they bring on another striker, a tall one, I don't want to go for a risk, we were already down to 10, to go to maybe 90 per cent, that's why I took him off but I think it's not too bad.”
After facing Betis in midweek, United host Fulham in the FA Cup on Sunday before heading into the international break.
There is also a chance that Garnacho’s role in Argentina’s matches against Panama and Curacao is under threat after he was named in the world champions’ squad.