Ben Gibson says Boro were left cursing a bad stroke of fortune after losing out to Brighton in the FA Cup.
"We never should have lost the game," he said. "A 0-0 would probably have been fair.
"I thought at times we played very well.
"In the end we were punished by a slice of luck, George [Friend] has cleared the ball, made good contact, and it's hit Glenn Murray and bounced in.
"Again, we looked more solid - we didn't look like we were going to concede and it's something stupid that's cost us.
"We gave a good account of ourselves, we're looking more solid and more like a team and that's a good foundation to build on. We've got to move forward to Tuesday."