Aitor Karanka delivered a half-time rocket to inspire 10-man Middlesbrough to an FA Cup third-round victory over Sheffield Wednesday.
The sides went in 0-0 at the break with neither goalkeeper having made a save, and Spaniard Karanka left his Premier League players in little doubt as to what was expected against Sky Bet Championship opponents after it.
Speaking after a 3-0 win during which defender Daniel Ayala was sent off, he said: "The second half was completely different.
"I told them at half-time that I thought we were playing a friendly game and for me, the FA Cup is not a friendly game, it's a really important game.
"Sometimes it's difficult when you go on to the pitch against a team in a lower division to get the right mentality and in the second half, we went on to the pitch with the right attitude, the right mentality and even when we lost Dani, we were really consistent.
"Everybody was committed, everybody was fighting for every single ball and that's the main thing for me."
Asked if he was angry as he welcomed his players back into the dressing room at half-time, Karanka added: "Yes, because the image that we were showing wasn't the right image. They came here knowing that they are in the Championship and they wanted to show everybody that they can compete against us.
"Now in every single football, if you don't go on to the pitch 100 per cent, you will have problems."
A crowd of 23,661 at the Riverside Stadium had endured a dreadful 58 minutes when Boro skipper Grant Leadbitter lifted the gloom with a perfectly-placed free-kick, although his side's cause was dealt a significant blow within seconds when Ayala was dismissed for a foul on Fernando Forestieri.
Ayala received a straight red card from referee David Coote after stepping into Forestieri's path with his appeals that there was cover arriving falling on deaf ears.
Karanka said: "At the beginning, I think it was a surprise for everybody. I haven't watched it, but someone has told me it is a red card."
Calm was restored when Alvaro Negredo blocked keeper Joe Wildsmith's attempted clearance into the net and the game was won long before Marten de Roon's strike in stoppage time.
Wednesday boss Carlos Carvalhal was understandably disappointed with the result, but far from critical of his players.
Carvalhal said: "We played our game, we moved the ball, we controlled the game. I am happy with my players and the way we played against a Premier League team.
"I am unhappy with the score, of course, but circumstances made us lose this game. We lose together and we win together. We don't put any responsibility on any player because it's a team work and circumstances of the game that everybody saw made us lose this game.
"It was not because we didn't try, we didn't put in our energy, we didn't play our football. The first and second goals, it was strange the way we conceded the goals and of course that makes a difference.
"We must give congratulations to Middlesbrough, but I am not unhappy. During the 90 minutes, we were not worse than Middlesbrough in this game."