Manchester United striker Joshua Zirkzee got off to a fast start for the club on his debut. Since then it has been a little mixed. When you play for Manchester United you are always 90 minutes away from becoming a hero, or villain. Just ask Casemiro. Joshua Zirkzee scored on his Manchester United debut, before accidentally causing a goal to be ruled out against Brighton. Against Liverpool he started his first Manchester United game and it was a struggle. Virgil van Dijk explained how he had a gameplan to stop him, and it largely worked. Zirkzee will still come good, it is all part of the learn…