Anthony Martial looked a "£100million player" and was labelled a "Ferrari" by Owen Hargreaves after Manchester United's Europa League win over Copenhagen.
France forward Martial won the penalty from which Bruno Fernandes scored to send United to the semi-finals via a 1-0 extra-time win in Cologne on Monday.
The Red Devils had 14 shots on target and hit the woodwork twice in the quarter-final tie, with Martial impressing while leading the line.
His performance drew praise from manager Ole Gunnar Solskjaer, who said: "He was sharp.
"Anthony has developed throughout the season, he was involved with the penalty.
"He's impossible to stop at times when he gets the ball into his feet and he drives at people, his balance, he can go either way.
"The only thing now is to put that ball in the back of the net again. I'm delighted with his performance, though."
Former United midfielder Hargreaves was equally effusive of his praise when commenting on Martial's fine performance for his role as a pundit for BT Sport.
"Everyone's got an opinion on Martial. He's a Ferrari," he said.
"He just looked like a £100million player."
Ex-United forward Robin van Persie was also impressed by what he saw and described Martial as "world class".
"The outstanding player for me tonight was Martial," Van Persie said. "When he switches it on, he's just too fast, too silky and wow, what a player.
"He is such a joy to watch. It's like he's having a kick-about in his own garden.
"What I like about Martial is he has an eye for his team-mates – he isn't just playing for himself. He always has an eye for his team-mates and that's what sets him apart from very good players.
"That's why I think he's world-class. He can provide, he can give assists, he dribbles, he's fast but he has great awareness of what's around him."
United legend Paul Scholes joined in the praise of Martial, who he feels is developing into a quality centre-forward.
"I like him, I've always liked him," Scholes said. "I thought is he a number nine or is he a wide player? He's turned himself into a number nine with every game I watch more and more.
"I think when he squares a player up and gets a run at him, I think he's unstoppable. I don't see how you stop him. He's only started showing it lately.
"He's got everything, he can beat a man, he can score goals, he's got everything you'd want in a centre forward."