Radamel Falcao felt Monaco lacked intelligence during their thrilling 5-3 Champions League defeat at the hands of Manchester City.
The striker had an eventful night on Tuesday, scoring twice - including a brilliant chip - but also seeing his second-half penalty saved by Willy Caballero.
Despite his miss from 12 yards, Monaco were 3-2 ahead before City scored three times in the final 19 minutes to claim the advantage.
And Falcao felt Monaco did not handle the closing stages of the last-16 tie well.
"It was a great disappointment, but we did not know how to kill the game," he told reporters after the match.
"Maybe we lacked a bit of intelligence. Coming up against players like that, they are unforgiving."
But Falcao is not giving up on a place in the quarter-finals ahead of next month's second leg.
He said: "It is still open for the return leg - nothing is finished. We believe we can do better at home and win."
Falcao, 31, now has 24 goals from 29 matches across all competitions this season.