Middlesbrough head coach Rob Edwards has said the manner of their Carabao Cup exit to League One side Doncaster Rovers was "unacceptable".
Boro were thrashed 4-0 at the Riverside by a Doncaster team that had changed all 11 players from their previous league game.
Edwards had seen his team win their opening Championship game with Swansea City on Saturday, but they were deservedly beaten by Rovers.
"I couldn't see that coming," Edwards told BBC Radio Tees. "It was a really painful night.
"The players know how we feel. Doncaster came here and played well but had a whole team of changes and deservedly won the game.