Memphis Depay has admitted he has misfired so far at Manchester United, having struggled to deal with the rigours of the Premier League.
Depay, signed for £25m from PSV Eindhoven in the summer, began his Old Trafford career impressively, starting all of their Premier League matches up to the 3-0 defeat at Arsenal in October, but has struggled for form as United have wilted on the domestic and European stage.
The 21-year-old said: "It's frustrating. I know I can do a lot better. I just had to settle in and get used to the football, to my new life in England. Failure just isn't an option.
"When playing in the Premier League, you have to be on top of your game every time. The difference is enormous.
"Defenders are physically strong, very fit and aren't afraid of anything. That was new to me. Good just isn't enough when you're playing for United."
Depay has come under fire this season from manager Louis van Gaal and his international coach at the Netherlands.
He was dropped from the Dutch squad in November with a critical Danny Blind stating "you must also function in a team - and he doesn't always do that".