Manchester United captain Nemanja Vidic says it's crucial they focus on one game at a time.
Vidic says the Reds must be wary of looking too far into the future.
He told manutd.com: "I'm trying to think game by game and the first one is West Ham away. It's been a hard match for United over the last few years and we have to be ready physically and mentally.
"It's great to be in competition for three trophies but obviously that doesn't mean anything if you don't win. It is not right to start thinking about trophies and playing City at Wembley [in the FA Cup semi-final] because one game can change everything.
"It would be a great achievement to win all three trophies but it will be very hard to do, especially if you look at the teams we are facing. It is possible, though."
