The 21-year-old, voted players' player and young player of the year at current club Troyes last season, played almost a full game in Leeds' 1-1 draw at Grimsby on Tuesday night.
Grayson said: "I thought he did well. He was unfortunate he was part of a poor team in the first half, but he won his headers, he wanted to get tight and tackle, and he looked a good player.
"He's only young, playing in a strange team and doesn't speak a lot of English, but I was pleased. We'll have to make a decision on him."
Leeds skipper Richard Naylor is in rehabilitation following back surgery and Grayson is keen to add cover to his squad for the start of the new season.