Bellingham struck the only goal of Wednesday night at the Santiago Bernabeu.
Xabi said afterwards: “Regardless of the goal, it was a really complete performance from him. It was a difficult game, with very little space, but I was really impressed with him against Getafe, and again today.
"Then he got the goal as well. I'm thrilled with him, but especially with how he won the all back time and again, and took up good positions in the box. I'm really pleased for him.
“He's got the ability to be involved in building the play, and the determination to get on the end of things too. He covers a lot of ground and he's so versatile. He knows how to break from the second line and he's got that hunger to score goals.
"He's one of the most complete players in world football and I'm fortunate to have him here. I ask him to take on a key role and get involved in the game. He's hungry to win, to score goals and to improve."
On the match overall, Xabi also said: “We knew it would be a hard-fought game and there were certainly moments. In the first half, we struggled to really get into the game early on but we settled down into it as time went by. We came out brilliantly after the break and we enjoyed our best spell after the goal.
"We had some great moves and we could have put the game to bed with several chances. Then we've got a wonderful goalkeeper who has the quality to stand up when it matters on Champions League nights. 1-0, three points, nine from nine, and we're happy.
“In the last few minutes we were 1-0 up and we had to defend the result. Juve threw people forward, they put the pressure on and had three forwards on the last line of defence. They asked a lot of questions but this is the Champions League and there are no easy wins. Juve are a European giant. There is a time for everything. Knowing what to do in each moment and enjoying it even when you're forced to dig in as a team is to be expected."