A spirited performance earned the Eagles a valuable point in Istanbul, with Yéremy Pino's clever finish and a stunning Jean-Philippe Mateta strike putting them 2-1 up.
But Besiktas ensured they took a point after Junior Olaitan found the net from outside the area in the 73rd minute to deny Sage's side the three points, which the performance deserved.
"I am satisfied with the performance," Sage told TNT Sports after the game. "A little bit frustrated for the lads, because they gave a lot this evening and I think they deserve better.
"We lacked concentration in the final minute of the first-half, at the end. It was the same thing when we were 2-1 up.
"In this kind of situation, you pay quickly if you make a little mistake.