Hayley Lauder admitted Glasgow City were "nowhere near good enough" in their heavy Champions League loss to SK Brann.
The SWPL winners trailed 3-0 at the break at Petershill and conceded a late fourth.
The sides meet again in Norway next Wednesday and Glasgow face missing out on the 16-team group stage.
"We were so far off it," attacker Lauder, who helped City reach the quarter-finals in 2020, told BBC Alba.
"First half, nowhere near good enough for this Glasgow City team. Second half, we got a bit more about us and tried to challenge higher up the pitch and I think we did that.
"Obviously their goal at the end, maybe we were pushing a bit more than what we could have been at that point in the game. It's hugely disappointing for me."
SK Brann won the previous two editions of the Toppserien but are fourth in their division after 22 of the 27 games of the current campaign. The Norwegian side are now in line for their Champions League group stage debut.
But manager Martin Ho cautioned: "It's half-time. If we can score four in this one, they can score four in the next leg."