Southgate told Boro's website: "He's only been here a couple of months and it's been a very difficult period for the team.
"I haven't felt it right to put him in yet and he totally understands that.
"He's taken a little while to settle in to the speed of the game. But he's still a very young player and we're trying to slowly bed him in to English football.
"We're very pleased with what he's done up to now, we think he's getting stronger and improving all the time.
"He's just having to be a bit patient because we have a lot of competition for places at the moment in the area of the field he plays in."