Saracens coach Alex Sanderson believes Maro Itoje, who made his club debut on Sunday, will become a "brilliant player" in the future.
The 18-year-old, who has come through the Sarries academy, looked like he was about to score a try on his first appearance for the Men in Black as he broke free early on, but the referee brought play back for a forward pass.
Former England flanker Richard Hill is known to have been impressed by Itoje, and Sanderson says he expects big things from the youngster as well.
He said: "I think Maro's going to be a brilliant player. You saw bits of him today [against Cardiff] and for his age at 106 kilograms he didn't seem to be lacking in physicality or the kind of attributes as a back rower out there today.
"So we're really happy with him and this was a test - he's had two exams this week, he's hardly trained, he came in friday having read all the lineout options we're going to use and all the plays we're going to use and slotted straight in.
"So it's a credit to him not just in terms of what a player he is but how he can step up to a level that's harder than what he's played at school and at school boy internationals so far."