BERLIN, Oct 17 - Borussia Dortmund stumbled to a goalless draw at Union Berlin on Saturday, with striker Konstantinos Karetsas suffering an injury on his comeback, but the point put them provisionally top of the Bundesliga table.

The Ruhr valley club, who lost 1-0 in the Champions League at Bodo/Glimt on Wednesday and have now failed to win any of their last three matches across all competitions, lacked spark in the first half, before upping their level after the break.

They then saw Karetsas, who had come on in the 62nd minute, go off with an ankle injury just eight minutes later. He had come back after collapsing in September due to what the club said were 'circulatory problems'.

The visitors had to settle for a second consecutive league draw that lifted them to top spot on 14 points.

Freiburg, on 13, are in action against Bayer Leverkusen on Sunday. Champions Bayern Munich, third on 11, take on RB Leipzig later on Saturday. REUTERS