Dortmund had the best chances to take the three points but were frustrated by the brilliant Ter Stegen on a night that also saw Lionel Messi make his first appearance of the season, coming on as a substitute. Ter Stegen made a string of fine stops, including Reus' spot-kick after Nelson Semedo had fouled Jadon Sancho, and a smart double save from the same player in the final stages of the game.
Barca have conceded seven goals in four games in La Liga, so a first clean sheet of the campaign will have been welcome even if it was largely down to Ter Stegen by himself. The German goalkeeper was the centre of attention before the game due to his ongoing battle with Bayern Munich's Manuel Neuer to be his country's No.1: the two exchanged words this week ahead of this game. He will have been happy, then, to do his talking on the pitch with a brilliant performance. A penny for Germany coach Joachim Low's thoughts?
Another sight to savour for Barca fans was the introduction of Messi in the 60th minute. He hadn't played previously this season due to a calf problem but looks ready to get back to work now.
Despite keeping the clean sheet, Barca didn't look much better in defence. There are still things to work on there. There will be even more to work on if Jordi Alba is ruled out for any length of time. The left-back was taken off in the first half with a hamstring problem. He will undergo tests on Wednesday.
There's plenty for Luis Suarez to work on, too. He looked poor. It now has been 19 games and more than four years since his most recent Champions League goal away from home -- against Roma on Sept. 16, 2015.
Manager rating out of 10
5 -- Ernesto Valverde was daring with his team selection, opting for possession in midfield and Ansu in attack, but his side were outplayed on the night. They had spells when they controlled the ball but created little and were second-best to Dortmund.
Player ratings (1-10; 10=best. Players introduced after 70 minutes get no rating)
GK Marc-Andre ter Stegen, 9 -- His international teammate Reus will be sick of the sight of him. He saved from Reus in the first half, from the penalty spot after the break and then made a double save from the same player late on. He would have been disappointed if Julian Brandt's shot, which smashed the crossbar, had taken away his well-earned clean sheet.
DF Nelson Semedo, 4 -- Asked to play out of position at left-back when Alba was taken off and was given a tough time by Sancho's speed and trickery. Fouled the English international to give the penalty away.
DF Clement Lenglet, 5 -- Not at his best either. Let the ball bounce a couple of times to put his side under pressure and was lucky to avoid a booking late on for nasty looking foul.
DF Jordi Alba, 6 -- Was heavily involved and a key part of Barcelona's attacking play before he was forced off injured.
MF Sergio Busquets, 6 -- Did OK but could have few complaints to have been withdrawn after the hour mark for Rakitic.
MF Frenkie de Jong, 6 -- Twisted and turned his way out of problems a few times but didn't hit the heights of his form in this competition for Ajax last season.
MF Arthur Melo, 6 -- Composed in possession and looked for the more attacking option, but too often was forced to take on the less risky pass.
FW Ansu Fati, 6 -- Became the youngest player to represent Barca in Europe, at 16 years, 221 days old, but couldn't follow up his heroics from the weekend. Showed a couple of flashes of what he's capable of at the end of the first half but was generally kept quiet by Dortmund.
FW Luis Suarez, 4 -- Returned with two goals as a substitute against Valencia on Saturday but looked like someone short of match fitness here. Touch? What touch?
FW Antoine Griezmann, 6 -- Some nice touches and movement but ultimately failed to deliver in the final third once again. Worked hard, but aside from his performance against Real Betis, he hasn't quite hit his best form as a Barca player yet.
DF Sergi Roberto, 6 -- Replaced the injured Alba, coming on at right-back as Semedo switched flanks.
FW Lionel Messi, 6 -- Made his first appearance of the season after recovering from a calf injury but unable to make an impact in 30 minutes on the pitch.
MF Ivan Rakitic, 5 -- Came on for Busquets for the final half an hour but couldn't make his mark on the game.