Head coach Aitor Karanka was unhappy with the attitude of his Middlesbrough team as their eight-game unbeaten run came to an end at Ipswich on Saturday.
It was Boro's first defeat since October and they now lie fourth, three points behind leaders Bournemouth.
"Today we thought we were better than we are," Karanka told BBC Tees.
"I have two feelings - the first is embarrassment because our performance was very poor and I'm not pleased because we lost the game.
"Last week at the Riverside I think we were thinking of the Premier League or Champions League, I don't know, and now I think that was the alarm to wake us up and let us know where we are and who we are."
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The Spaniard has had a huge impact at the Riverside, guiding Middlesbrough to 12th last season, having taken over in November 2013 with the club in the bottom half of the table.
This term has been even more impressive, with a fluid attacking style matched by a solid defence maintaining a top-four place, although Karanka believes mentality was the crucial factor lacking at Portman Road.
"The most important message is to change the attitude," he continued.
"If you lose or don't play well but your attitude is good, it is easy for me to understand it, but I didn't like the attitude today.
"This team, when we've not played well, the following game has been good, so I would like to think that we will be good on Friday [against Nottingham Forest]."