José Mourinho praised Yan Diomande's "incredible potential" but said the winger still has "a lot to learn" after making his first start for Real Madrid in a 4-1 LaLiga win over Rayo Vallecano on Saturday.
Goals from Kylian Mbappé, Álvaro Carreras and Jude Bellingham put Madrid 3-0 up at halftime at the Bernabéu, before Sergio Camello pulled a goal back for Rayo, and Mbappé scored another in added time.
Diomande - Madrid's record signing - had only made brief substitute appearances since arriving from RB Leipzig last month, but featured for 72 minutes on Saturday.
"Diomande is improving progressively," Madrid coach Mourinho said in his post-match news conference. "He hasn't been involved in top-level European football very long. He's had the last season at Leipzig and not much more. He has a lot to learn tactically.
"But you can see he has incredible potential in one-on-ones, his crossing, and his shooting. He's a very strong player who gives us a lot of options. He can play in [Vinícius Júnior's] position, or on the right ... I want to see Diomande evolve, because I know what the other [players] can give me."
Mourinho said his players had been fatigued after a tough Champions League win over Inter Milan in midweek, as they began to struggle as Saturday's second half went on.
"It was a 45-minute game," the coach said. "Forty-five minutes, game over, there's nothing else to say. I knew the team didn't have the physical or mental strength to continue in the second half as they had played in the first. Jude Bellingham played the last 10 minutes almost without any energy.
"It's physical energy, but it's also mental, dropping off not just the intensity, but the concentration, making more mistakes ... I knew with my Champions League experience that the game was going to be like that. We wanted to start strong and finish the game off and that's what we did."
Vinícius - who was whistled by some fans in midweek - provided the assist for Bellingham's goal, and was embraced by Mourinho when he was substituted late on.
"Physically he's better than ever, he needs just a millimeter to get to his top speed," Mourinho said. "Mentally he's very strong. He knows Real Madrid better than anyone ... Right now it's about assists and understanding the defensive side [of the game], and the goals will come."