In a Champions League clash with Atletico Madrid on Wednesday, the confident 19-year-old striker saved the Red Devils a draw.
Manchester United substitute Anthony Erlanga got a job for Ralph Lonnick before setting foot at the Wanda Metropolitano stadium on Wednesday night: freaking out Atletico Madrid defenders.
It took the teenager just five minutes to achieve his goal with a single touch, with the Swedes drawing 1-1 with the Spanish champions in the first leg of the Champions League round of 16. Bruno Fernandez passed the ball all night and then calmly finished Jan Oblak.
Perhaps, if the selected striker had shown the same ruthlessness in the game, United would not have found themselves in need of a young substitute to save themselves.
Erlanga is certainly not as good as someone who has played more in the Youth League this season than the Champions League.
His goals exude composure and confidence, and he is not intimidated by the hostile atmosphere created by the home fans.
"I've dreamed of a moment like this, scoring a goal in the Champions League against a top European team like Atletico Madrid," he said. ”
"I told you how calm and uncool I am and whenever I have the chance, I want to give back to the manager for 150 per cent every time I step onto the pitch.
"I just do what I can. I want to be the best player on the pitch and I appreciate the boss. ”
If the 19-year-old gets his wish, he will leave the club on loan at the January transfer window, but Ronnick has seen enough of the situation to know he wants him to stay.
Before he took charge of his first training, the 19-year-old was the best.
"He really played like a dream come true," Lonnick told reporters after the Madrid match. "It was a joy and a pleasure to watch him play.
"I hope some of the other players will follow his example and role model.
'I think now he's just showing the possibilities of football with the right mindset, the right way, because that's exactly what he does and what he always does in every training session.'
The German boss didn't name the team members who disappointed him, but after the first half of the performance at the Mets, you could have put most of the team in that position.
United know what will happen to them. The raucous atmosphere in Leeds on Sunday was just a warm-up on Wednesday night.
Hours before kick-off, thousands of Atletico fans lined up in the streets around the stadium to welcome the team coach in a hostile manner, while United's players were booed and ridiculed every time they touched the ball.
It was a moment when the biggest star in the team needed to stand up, but on the contrary, especially in the first half, they seemed overwhelmed by the occasion, looking nervous and lacking in intensity and motivation.
Thanks to Lonnick's change, United found ways to turn things around.
With a quarter of an hour left in the game, Elanga finished in five minutes what Jayden Sancho, Marcus Rashford and Cristiano Ronaldo failed to achieve between them: a shot to score.
Given his recent form, Sancho's quiet night is forgivable, but the way Ronaldo and Rashford struggled was worrying.
Ronaldo has had a lot of joy with Atletico in his career, but he won't add this 1-1 draw to any classic game in his memory.
As for Marcus Rashford, he is now completely out of date.
Of course, he's not the only player with poor passes and problematic decisions, but when you also consider his lack of goal threats, it's hard to support him in starting this weekend's game against Watford.
Marcus Rashford's talent is undeniable, but he is currently going through a difficult period and his confidence has been affected.
"He looked too anxious for me; he looked almost too hard," Paul Scholes said.
"Every time the ball passes to him, it almost feels like he's trying to do something magical. It's probably the worst thing you can do. ”
The contrast between Marcus Rashford and Erlanga could not be more obvious.
The Swede looks cool, calm, confident and most importantly, he is giving Ronnick what he wants from his players.