Pavel Vrba lamented Czech Republic's defensive frailties, despite Monday's 4-2 victory in Kazakhstan.
Czech Republic preserved their 100 per cent record in Euro 2016 Group A qualifying by defeating minnows Kazakhstan at Astana Arena.
Borek Dockal, David Lafata, Ladislav Krejci and substitute Tomas Necid were all on target for the Czechs, who made it three wins from as many games.
However, coach Vrba was not completely satisfied after his side failed to keep a clean sheet for the third qualifying match in succession.
"After three matches we have nine points but I have to stress that it's still only the beginning of qualifying," said Vrba.
"I'm not really happy with our results because we keep conceding goals and failing to keep clean sheets.
"Kazakhstan are good going forward, though, and I really thought the number nine [Bauyrzhan Islamkhan] had a good game."
The Czechs were in cruise control approaching the hour-mark - enjoying a three-goal lead - before Kazakhstan defender Yuri Logvinenko scored twice in the final seven minutes.
"In the first half we were actually playing well but in the second, when the score went to 3-0, we started losing concentration - you saw the consequences of that," Vrba added.
"The score is a fair reflection of the match in my opinion. In the second half, Kazakhstan upped their game and in the end both teams could have scored more."