Slovakia coach Jan Kozak praised his team for rebounding from Gareth Bale's opening goal and said "luck" was all that separated the sides in Wales' 2-1 win in the European Championship opener on Saturday.
After Bale's dipping free-kick in the first half, Slovakia responded with an equliser when substitute Ondrej Duda bundled home after the hour mark. But Hal Robson-Kanu's winner nine minutes from time decided the contest.
"Of course any defeat is unpleasant, especially at a Euro," Kozak said. "I knew whoever scored first would have a big advantage as Wales have a well-organised defence.
"After we conceded we were not really comfortable on the ball, we lost possession, but after half-time we did our best and equalised.
"Towards the end both teams tried to win, it was an open game, and they had a bit more luck."
Kozak said a change in strategy at half-time helped his team level the score.
"At half-time, I talked to the full-backs. I told them to be more active in attack," Kozak said. "I think [Robert] Mak and [Vladimir] Weiss did get more support from the full-backs after that.
"When I brought on Duda and [Adam] Nemec it was a bit of a risk, but you have to deal with these scenarios. We could have prevented the second goal, but that's football."
Duda scored almost immediately after coming on, but he was of mixed emotions after the defeat.
"I don't know whether to be happy or not," he said. "Of course I'm glad about the goal, but my feelings are not the same as if we'd won the match, or if it had been a draw, so it's kind of strange.
"We were just lacking some luck, because they scored a goal where the player didn't hit the ball properly, but unfortunately for us, it went in."
Kozak admitted that Wales had put themselves in a strong position to make the knock-out stages, even before England and Russia shared the points in the other Group B game later on Saturday.
"The result for them is great, to get three points in the opening game is a great boost for confidence," said Kozak. "They now have a derby and that is a great motivation for them.
"It's difficult to anticipate the result, they have two matches to get the results they need, and they have a very good chance to qualify now.
"Wales have a well-organised defence and up front they have a very dangerous man [Bale] who can make a difference."