Scotland manager Steve Clarke declared their loss in Slovakia a "defeat but not a step backwards" after his side failed to capitalise on a series of chances in Trnava.
A deflected long-range strike from Jan Gregus in the 31st minute consigned Scotland to a 1-0 defeat – their first in 10 matches.
However, there was "more than enough" to encourage Clarke from the performance.
Scotland rarely allowed Slovakia to breach their defence and home goalkeeper Marek Rodak pulled off brilliant stops from Kenny McLean and substitute Leigh Griffiths, as well as more routine saves.
Clarke, who made eight changes following Thursday's play-off win in Serbia, said: "When you have such a long unbeaten run it's always disappointing when it finishes, but it finished in the right way. The team performance was good.
"It was a defeat but it's not a step backwards. There was a lot to build on.
"I thought we started a little bit too deep, seemed too hesitant, but that was understandable. It was a long night for us – for both teams – on Thursday, and a successful night for both teams.
"It took us a little bit of time to find our way in the game but once we did I thought we were really good, created a number of good chances. On another day.
"I am not going to gripe about a lack of luck. We have had a little bit on our side recently.
"Their goal was a big deflection and aside from that I thought we defended well."
Scotland missed the chance to go 10 games unbeaten for the first time since 1927 but they remain top of their Nations League group ahead of their final game in Israel on Wednesday and Clarke has a positive message for his players.
"I told them an unbeaten run is going to end sometime," he said. "There is a way to lose the game. We played well, we deserved more out of the game.
"But everything we want to do in this section is still ahead of us. We have to start the next unbeaten run, hopefully winning run, in Israel on Wednesday."
Oli McBurnie squandered three first-half chances to break his international duck on his 14th cap.
The Sheffield United striker took a heavy touch after being played through by Ryan Christie then took too many touches after being set up by Stuart Armstrong.
The forward then headed straight at the goalkeeper from 10 yards after beating his marker to Liam Palmer's cross.
Clarke said: "His performance was good. He did what he was in the team to do, which was to allow Ryan Christie and Stuart Armstrong to get up and support.
"He had one very good chance in the first half which he couldn't quite get his shot away. It was excellent defending.
"He just has to keep doing what he's doing. His work-rate, his effort for the team, was first class. The goal, if it comes, will be very big for him but he shouldn't let it weigh too heavy on his shoulders."