Despite going ahead in the first half, Freiburg were unable to take the win and now face a tough test to qualify from the group.
"We are a bit disappointed that we didn't pick up the three points," he told UEFA.com. "We have worked a lot and played good football but in the end it wasn't enough for victory.
"Sometimes we didn't get that piece of luck maybe needed to score the second and that's the reason we only have one point at the end. We will not travel to Estoril to lose - we will give it our best, we will fight, and maybe that'll enough for three points: that would be the best outcome, of course."
Freiburg are also struggling in the Bundesliga and currently sit 17th.