Aberdeen manager Derek McInnes hopes the warning has been heeded as his side must step up a level in the Europa League this week.
The Dons toiled through the first qualifying round against Luxembourgish part-timers Fola Esch last Thursday, losing 1-0 in Luxembourg but still going through 3-2 on aggregate.
The manner of the defeat angered the manager although he does not expect a repeat when Latvian side Ventspils visit Pittodrie on Thursday for the second qualifying round first leg.
McInnes said: “Last week is a constant reminder that no matter how talented we are as a group, work-rate and intensity is vital.
“Nobody is ever going to give us a victory, we have to work for everything we get.
“We have to make it hard for the opposition and get our hands dirty at times.
“I have always felt we’re at our best when we make life difficult for the opposition when we don’t have the ball.
“So it was a reminder for us, but it’s not something that has been common in my time here and it’s not something I expect to happen again.
“We have to take the warning from it and take it into the next game on Thursday.”
Following Thursday’s shock loss the Dons manager said he would analyse what went wrong in the build-up to the trip to Luxembourg.
However, having reflected on the game, McInnes is confident the lessons have been learned.
He said: “I don’t want to dwell too much on it, but as a staff it’s important we look at why the performance was how it was.
“It showed that if the approach isn’t right from the start then we are in trouble.
“We were not at the level of intensity we wanted, whereas they approached it the way it should have been.
“The penny dropped with a few of them when we only had 10 fit men on the pitch with 20 minutes of the game remaining due to Willo Flood’s back injury.
“I could see a few of them think ‘we’re in trouble here’ and they dug deep. We put the game at risk over there so it’s a learning curve and we have had our warning now.”
McInnes will spend the week preparing for a new foe in Ventspils and his early reports show a side who will be a step up on the threat presented by Fola Esch in the first qualifying round.
He said: “We have watched Ventspils on video and also had people at their game over the weekend.
“They like to play 4-4-2 and have a powerful front two.
“They are technically very good and get crosses into the box early.
“They look a decent side who are well-organised, so it’s going to be another tough game.”
The Dons manager expects Ventspils, who are managed by Englishman Paul Ashworth, to be well prepared for what to expect from his side at Pittodrie and has challenged his players to show their credentials.
“They have an English manager so that adds another element to it because he will be more familiar with us than we otherwise might find.
“He will also likely have good contacts here who he can ask about us to find things out. I envisage another tough game this week. But I want us to show why we are in European competition, do the things we know we’re good at and produce a strong performance – because we will need it.”