Cardiff Blues head coach Danny Wilson bemoaned his team's second-half showing in their 14-13 loss to Leinster at Cardiff Arms Park.
The Blues did well in the firsthalf and, despite playing in to a strong wind, trailed only 6-3 at half-time.
But they did not take advantage of the wind after the break which left Wilson frustrated.
"After all the hard work we did in the first half in the second half we let it get away from us," he told the BBC.
"Our execution of the game plan in the first half was excellent, the boys played into the wind really well.
"In the second half our execution of the game plan was poor."
The Blues came close to securing victory when when Josh Navidi crossed for a converted try which brought them to within a point with three minutes left on the clock.
But a drop-goal attempt from Rhys Patchell in the last-minute was charged down by the visitors.
The defeat means the Blues are ninth in the standings, and it's there second successive loss after they suffered a shock 13-7 defeat away to Treviso last weekend.
Wilson fears these two defeats could come back to haunt them later in the season.
"Last week was a huge missed opportunity and I feel the same this week," he added.
"For us to have a real good crack and trying to get in to that top six we needed to win either last week or this week and we've failed to do so."