A deflected effort from Stewart Downing and a late strike from Alex Pattison were enough to see Boro's winning start to pre-season continue.
“It hasn't been the best game to watch," Karanka said. “But we add another training session and arrive home again without injuries.
“We are working hard, and have a lot of new players who weren't here last season.
“For that reason, it's difficult to train tactics – we're thinking more about the physical side."