Alejandro Garnacho's reaction after Joshua Zirkzee's early substitution during Manchester United's defeat to Newcastle has emerged.

United fell to a 2-0 defeat to Newcastle in the Premier League clash on Monday night at Old Trafford. Early goals from Alexander Isak and Joelinton saw the Reds fall to a fourth consecutive defeat in all competitions and third in the top flight.

Ruben Amorim opted to start Joshua Zirkzee in the defeat, but the Netherlands international was withdrawn in just the 33rd minute to be replaced by Kobbie Mainoo. There were sarcastic cheers followed by a round of boos by sections of United fans during the substitution, although it's unclear if the reaction from supporters was aimed at Zirkzee or the disappointment at the first-half performance of the team.

Zirkzee walked down the touchline and into the Old Trafford tunnel after the substitution before eventually returning to the dugout. As the United striker walked back down the touchline, he did so as several of his teammates were warming up in front of the home fans.

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Garnacho was one such player, and videos have surfaced online showing the forward urging United fans to show their support for Zirkzee. As Zirkzee walked towards the dugout, Garnacho could be seen raising his hands in applause for his teammate and appeared to want the home fans to do the same.

United agreed a £36.5million deal to sign Zirkzee from Bologna in the summer, with the striker scoring four goals in 27 appearances in his debut season at Old Trafford. After the defeat to Newcastle, Amorim explained why he decided to substitute Zirkzee before half-time.

"I talked with Josh [Zirkzee] about that, because it's important to express the message, but I'm always thinking about the team, and, in that moment, it was important for the team [for] Josh [to] go out," Amorim told Sky Sports following the result.

"You have to think about the team and also, sometimes about the player, because the player is suffering. I was there a few years ago and I know that he wants [it], because I saw it during the week, and that's the most important thing."