Sporting CP assistant coach Raul Jose believes a lack of aggression cost his side in the 2-1 Champions League Group F defeat to Borussia Dortmund.
Fine goals from Pierre-Emerick Aubameyang and Julian Weigl were just reward for a superb first-half display by the Bundesliga outfit.
The hosts were a different proposition after the interval, though, and substitute Bruno Cesar blasted home a close-range indirect free-kick to halve the arrears.
However, Sporting were unable to find another way through a Dortmund defence that creaked its way towards the final whistle.
"We still managed to create a few chances in the first half, but we were not as aggressive as we should have been and we let our opponents score twice," Raul Jose said, as quoted by UEFA.com.
"In the second half we were stronger, we played more aggressively and, with a little bit of luck, we could have got at least a draw.
"In the Champions League details are what matter and that was what made the difference today."
Sporting lie third in Group F and could be eliminated if they lose the return match at Signal Iduna Park, but Raul Jose is remaining upbeat.
"I believe that we are still in contention for a place in the next stage and I believe we can get a win in Germany," he added.
Bruno Cesar emphatically capitalised after Roman Burki handled Marc Bartra's backpass but, as in the earlier round-robin game at Real Madrid, his goal could not prevent a 2-1 defeat.
"We conceded a goal very early in the match and it's always difficult when you have to run all match to turn around a result," said the 27-year-old Brazilian, as quoted by UEFA.com.
"In the second half we put our opponents under pressure, we played with more spirit, we tried everything and we managed to get one goal back, but we could not do more.
"Now we will fight to do in their home what they have done in ours."