Patrice Evra knows at first hand the damage complacency could do to Manchester United's bid to reach the Champions League final and he has warned his team-mates to avoid a "disaster".
Only a heavy defeat to Schalke at Old Trafford next week can end their hopes of playing in a third final in four years after their 2-0 win over the German side in Gelsenkirchen on Tuesday night.
It seems highly unlikely yet Evra knows the improbable can sometimes turn out to be possible, as his own career shows.
"In football you never know,'' the France defender said. "I remember playing for Monaco in the 2004 quarter-final and we played in the Bernabeu against Real Madrid and lost 4-2. Real thought they were going into the semi-final. They thought they were there already. But in the second leg we won 3-1 and went through.''
Evra believes that tie provides a valuable lesson and will ensure his team-mates do not get too far ahead of themselves and start dreaming of a Wembley date with either a Real Madrid side containing United old boy Cristiano Ronaldo or Barcelona, who gave them a footballing lesson during the 2009 final in Rome.
"We have to be as professional next week as we were last night and keep going,'' Evra said. "We have to win at Old Trafford. But I must say if we don't go through to the final now then it would be a disaster for Man United.''
Providing United retain the same mentality, Evra is certain they will make it. Certainly, there was little evidence last night of a team capable of going to Old Trafford and making a game of it, even if the 5-2 win at Inter Milan in the previous round shows what Schalke are capable of.
"We just have to do our job,'' Evra said. "We are very near to the final now but we have to complete the task we have started. I am not surprised we did well and the game was one-sided because we showed Schalke so much respect. We respected them a lot. Before the game we just said we play the semi-final and that it didn't matter who our opponents were. That was important in playing the way we did.''