Manchester United boss Sir Alex Ferguson wants his side to be more clinical in their Champions League decider against Benfica on Wednesday.
United faltered in their games against FC Copenhagen and Celtic and still need a point from their final Group F match at Old Trafford to go through.
He told the club website: "It won't be an easy game but as long as we remember to finish teams off we will be OK.
"That's going to be an issue, when we get chances we've got to take them."
Ferguson added: "This is a game you can't trifle with. It's too important for us. If we get chances we have to take them, but I think we've got a chance."
Last season, Benfica eliminated Liverpool before losing to eventual winners Barcelona in the quarter-finals.
United failled to qualify for the knockout stages last season and finished bottom of the group after losing to the Portuguese champions.
Defender Rio Ferdinand is confident United can raise their game for the decisive tie at Old Trafford but echoed his manager's warning over the forwards' finishing.
He said: "The big games - when people are asking questions about us or think we won't do well - we seem to come through it. This is an opportunity to do that again.
"In the Champions League, you must kill games off when you are on top - because the other teams always have that quality and ability to put the ball in the back of the net."
Benfica coach Fernando Santos believes his side are capable of causing an upset against United for the second successive season.
He said: "The match against Manchester United is a real final for us.
"We believe victory is possible and trust we will also have a bit of luck.
"Qualifying is very open because United are not as strong in recent weeks as they have been."