Neil Warnock lamented some poor defending but remained upbeat after Boro were squeezed out by Watford at Vicarage Road.
Boro's boss watched his team fall behind to a Craig Cathcart header on 11 minutes.
The Teessiders toiled to get back into the contest in a cagey affair which produced only a handful of clear-cut chances beyond that as the home side came away with victory.
"It was a bad goal to concede, but that's the only disappointment," Warnock said.
"I thought we played very well, we just couldn't quite get the ball in the net at the other end.
"They're at home, they've come down from the Premier League, and we were far better in a lot of the phases of the game. They were timewasting in the second half which just shows, and I thought Marcus Bettinelli was playing centre-half for most of it.
"The performance was super, I thought, against a top side."
Taking chances was the main note for improvement, a familiar tune from the Boro manager.
"You're not going to get 90 minutes, but I thought we played most of the football," he said.
"We're only a young side, and I thought we were the better side tonight with the chances we created.
"We've got to put it in the net, it's the usual thing from the last couple of years. We've just got to keep persevering."
Warnock was pleased to add a third summer incoming in Sam Morsy earlier today, and has eyes on further recruitment.
"We needed an addition in there, and we've managed to get Sam over the line," he said.
"It's strikers we're looking for now - it would have been nice to have a fresh pair of legs to bring on.
"We've got one or two other targets and we'll be working hard to try to get someone in before the Bournemouth game."