Dortmund beat bottom dwellers Hertha
Turkey international Sahin converted a 60th-minute penalty before Argentine Barrios added a second goal in stoppage time as Dortmund moved up to ninth spot with 16 points from 11 games.
Leaders Bayer Leverkusen travel to fourth-placed Schalke 04 on Saturday while second-placed Hamburg SV, level at the top on 22 points, entertain lowly Borussia Moenchengladbach.
Mats Hummels should have given Dortmund the lead six minutes before the break but headed wide from a cross by Sahin.
Paraguayan Nelson Valdez was also denied by Jaroslav Drobny just after the restart but Sahin had no trouble sending Hertha's keeper the wrong way from the penalty spot after Gojko Kacar fouled Patrick Owomoyela.
Hertha, who have lost nine of their 11 league matches, came close to an equaliser when Lukasz Piszczek hit the post.
Barrios then sealed Dortmund's win with his seventh goal in seven matches, a superb turn in the box and a powerful strike giving Drobny no chance.