Jose Morais said he was 'surprised' by Barnsley's first half showing as the Reds went down to Middlesbrough at the Riverside.
First-half goals from Daniel Ayala and Adama Traore were followed by a third from Patrick Bamford after the restart to put Boro on course for three points against the Tykes.
But Barnsley pulled one back through Keiffer Moore and for the last 32 minutes there were real signs the visitors could have made an even closer game of it.
In the end Middlesbrough stayed resilient to claim the victory.
Tykes boss Jose Morais, who has won one of his five matches in charge, said: "We knew it was a difficult opponent, with quality players.
"We were aware of situations that could happen in the game and for some reason we didn't control it in a good way in the beginning and I believe in the first half we had problems to keep our organisation.
"This has happened in some games, we wanted to correct it and we couldn't.
"I was impressed with the second half, I was surprised with the first half. I believed the team can do what they did in the second half.
"That is what I wanted and the players wanted, we wanted that for the whole game. That is what we have to work on to achieve the results we want in such a competitive league with opponents who have quality.
"I'm aware of what we need to do to be in a better position. We have played four games away, we knew this was against Middlesbrough, a good team with good players, a team that has been improving.
"Most players here have played in the Premier League. To play against good teams is when you can be extraordinary and this was an opportunity to do it... we couldn't do it but we have other games to play and I believe they can do what they can."