Pioli insists they can be happy with the point.
“We wanted to win, we deserved to in the first game and knew the difficulties we were going into. We got a few passes wrong and were not precise enough technically, but it was a great second half performance and we certainly created the opportunities to get the victory," Pioli told Sky Italia.
“The fact we didn't manage that is disappointing, but we have to look to the future with confidence. Inevitably, we lacked precision in front of goal and were not effective enough in the opposition penalty area.
“It is also true that Dortmund created problems for us. It was a classic Champions League game against an energetic, tough and intense opponent, we fought it out with them on every ball.
“We knew this was going to be a complicated group. There was a surprise result, but that could end up being in our favour," added Pioli.
“Great concentration will be required and we know that we cannot get a single thing wrong from now on, because qualification is very tough. It was clear from the start this was the toughest group in terms of quality, the level is very high throughout and the next game with PSG is going to be very important."
On striker Rafael Leao, the coach added: “I think Rafa had a very good game. People always expect him to do something exceptional, he can be allowed a few errors. He was a constant thorn in the side of the Dortmund defence, but not winning these games does leave you with regrets.
“We need to work on these situations to be more clinical, because the performance was there and we just need that extra step."