George Friend says that ten-man Boro were on the wrong end of fine margins as Sheffield United inflicted our first league defeat of the calendar year.
An impressive run of away results in the Championship was brought to an end after Richard Stearman's second-half header.
"It was tough, similar to last year with having a man sent off," Friend said.
"And losing Flinty (Aden Flint) was tough as well.
"It was tight, the margins were fine and we felt a couple of things didn't go our way, especially in the build-up to the goal.
"It's disappointing but we've got to keep our heads up. We've got a huge game on Sunday now."
Watch the full interview with George Friend in the video player above.