Monaco coach Leonardo Jardim has described his team's goalless draw against Lille as "a blemish".
AS won their first game away to Nice last weekend, but were unable to break down Les Dogues at the Stade Louis II.
However, Jardim is convinced that Les Rouges et Blancs didn't perform to their potential in the second half.
He is quoted by Ligue 1.com as saying: "We played a good first half. We had three chances to score. Injuries to (Layvin) Kurzawa and Joao (Moutinho) are not ideal.
"We did not enough to win. It is a blemish, dropping two points at home. Our substitutions didn't work as they did against Nice. In Nice they changed the game.
"The second half was difficult. Over the last ten minutes, Lille even created two chances. It is always easier if you have a left-back on the bench, but we cannot have all positions. There is always a choice to make."
Monaco travel to Valencia for the first leg of their Champions League qualifier on Wednesday.
