Barcelona coach Hansi Flick said on Friday that Lamine Yamal must work hard and continue to replicate his performance against Inter to reach levels of Cristiano Ronaldo and Lionel Messi.

Yamal, 17, scored Barcelona's first goal in a three-pointer in the first leg of the Champions League semi-final on Wednesday, earning praise from his performance worldwide.

International coach Simone Inzaghi posted him a talent that only appears every 50 years, and Flick called him a genius after the game.

When asked what the next step is Yamal, Flick said before Saturday's Laliga game against Real Valladolid: "He knows what I want."

"When you can play the game at this level, you have to show it again. It has nothing to do with a game. Every player has the potential to get better, and that's what he needs.

“It’s not only his talent, his genius, but it’s also hard work when you want to get to that level, (like Cristiano), Ronaldo, (Lionel) Messi), who used to be big big players.

“We all have to stay calm and let’s see what happens. We’re so glad he played with us and he was at this level when he was 17, which was incredible.

"We know he has to work hard (maintain) this, maybe getting better and better. I think he wants this, too. It's not the ending."

Yamal, who scored 15 goals and created 24 goals this season, was one of several players that Barça could take a break when he headed to Valladolid in Laliga on Saturday.

Flick said the second leg will change against the International Front, while goalkeeper Marc-André Ter Stegen will make his first appearance since his injury in September.

"Mark will be back," Flick revealed. “He performed very well. He performed great in training.

"I think it's also good to have Tek (Wojciech szczesny) recovered a little bit. I didn't think about the (determined) change before the end of the season. It's Valladolid game and then we saw it."

Although Barcelona will spin with Valladolid, who confirmed a relegation of the second division last week, they can't afford much.

On the highest flight in Spain, they led Real Madrid, and they Classic On May 11, in pursuit of high notes, only four points were on the top of the table.

“Lariga is the most important thing (the trophy),” Flick added. “When you win this title, it’s an honest title. In a long and long season, you have to play at the highest level.

"Where will Valadolid play next season, they are in Laliga now. We respect them. We focus on them. You can lose the Laliga championship in these games."

Barcelona has won the first round of three possible, Copa del Rey, the injured trio of Alejandro Balde, Robert Lewandowski and Marc Casadó, all three struggled to return to Inter.