Andy Robertson admitted Scotland "didn't turn up" in the first half of their chastening 5-1 defeat to Euro 2024 hosts Germany on Friday.
Backed by a vocal travelling contingent in Munich, Scotland were chasing their first major tournament victory since the turn of the century but were torn apart by Julian Nagelsmann's side.
Florian Wirtz, Jamal Musiala and Kai Havertz netted as Scotland went into half-time three goals and a man down, having seen Ryan Porteous sent off for a wild challenge on Ilkay Gundogan.
Substitutes Niclas Fullkrug and Emre Can then scored in the second half either side of an Antonio Rudiger own goal, as Scotland conceded five goals in a game for the first time since a 5-1 friendly defeat to the United States in May 2012.
At the other end, Scotland failed to record a single shot on target in a major tournament match for the first time since a 1-0 loss to the Netherlands at Euro 1992.
Speaking to ITV Sport after the full-time whistle, Liverpool left-back Robertson said Scotland's players had let boss Steve Clarke down.
"In the first half we didn't really show up. We weren't aggressive enough, we let good players on the ball," Robertson said.
"They obviously had a gameplan, like we did. Their gameplan worked a million times better than ours but it wasn't because of the practice, it was because we didn't put it together on the pitch.
"When big occasions like this come, you have to do that. In the second half, down to 10 men, I thought the lads dug in really well, to be fair to them.
"We could have drawn the second half but it's no consolation. We're well backed here with so many supporters, and today was hugely disappointing.
"Playing against the host nation in the first game, you don't get much tougher than that. But we have to bounce back quickly because there was a lot of things wrong today."
Scotland's defeat was their heaviest at any major tournament since the 1954 World Cup, when they were trounced 7-0 by then-world champions Uruguay.
They have five days to put the result out of their minds ahead of their second Group A match, against Switzerland at the RheinEnergieStadion in Koln.
"It's a reminder of how tough this tournament is. You're playing against world-class players and their players turned up all over the park," Robertson added.
"They had an answer for everything we had. Sometimes that happens but if we sit down, we can't think we played to our maximum, and you have to do that.
"We have five days to sort ourselves out and go again, it will be another tough test against Switzerland. We'll take tomorrow to be angry at ourselves but then come Sunday, we have to be positive."