Poland midfielder Bartosz Kapustka was annoyed with himself after a moment of second-half madness cost him a place in the squad for Saturday's Euro 2016 last 16 clash with Switzerland in Saint-Etienne.
The 19-year-old was cautioned for a senseless challenge on Andriy Yarmolenko on the hour mark in their 1-0 defeat of Ukraine that ensured Poland's progression, his second of the tournament incurring a one-match suspension.
"It was definitely avoidable," he said. "I thought it was going to be a little challenge and didn't realise it would be so significant.
"I am angry with myself, I gave the referee a reason to give me a yellow card and that makes it so hard to digest."
Despite the individual setback, Kapustka was pleased to have played a part in a Poland win.
"Of course, it was important, it makes us happy," he added. "Perhaps we didn't play as well as we did in the first two matches but Ukraine had a lot of the ball.
"We knew their wingers would be their dangermen, I probably spent more time working defensively than offensively.
"We knew they'd be motivated, they had nothing to lose. They wanted to leave this tournament proudly and we knew it was going to be a difficult game."
On Switzerland, he said: "It's going to be tough. Switzerland have some players who can play but, nevertheless, I think we can beat them. We haven't conceded yet [at Euro 2016] and I think that makes us favourites."