Wayne Rooney insists Manchester United must be at their best against CFR Cluj to avoid a repeat of last season's UEFA Champions League woe.
United failed to advance past the group phase last term and have again been drawn in a relatively benign pool containing Braga, Cluj and Galatasaray.
The Red Devils scrambled past Galatasaray in their opening game a fortnight ago and Rooney says United must not take a trip to Romanian underdogs Cluj on Tuesday for granted.
"The Champions League is completely different to the Premier League," said Rooney. "If you are not at your best you get punished, which is what happened to us last season.
"We have to make sure that won't happen again this year so this is a big game for us.
"Hopefully we will get a win which will put us in a good position to go through so early on in the group."
The 26-year-old is certainly up for the challenge given how highly he still rates the Champions League experience, adding: "I still think it is exciting. It is a great competition to be in.
"You look at the teams involved and it is a great challenge for everyone. It is something I love playing in."
Meanwhile, Sir Alex Ferguson has confirmed he will not be taking any chances with his team selection against Cluj, who beat Braga away from home two weeks ago.
The United boss said: "We will play the experienced players on Tuesday.
"Cluj knocked out Basel over two legs in the qualifier and that shows where they are.
"They won in Braga, it's not an easy place to go to. We are taking it seriously. They think they can qualify now.
"They have a home game against United, get something and they are in a good position."