Marco Reus scored a dramatic injury-time equaliser to salvage a 1-1 draw for Borussia Dortmund against Cologne in Saturday's Bundesliga encounter at the RheinEnergieStadion.

The home side appeared to be on their way to victory thanks to Artjoms Rudnevs' first Bundesliga goal of the season, the former Hamburg man breaking his duck with a fine header in the 28th minute.

Anthony Modeste, Cologne's top scorer, then missed a gilt-edged chance to make it 2-0 early in the second half.

And that proved costly when Reus turned in Adrian Ramos' assist late in the day to salvage a point for Dortmund, while Cologne's misery worsened when Salih Ozcan was sent off for a second bookable offence in the closing stages.

BVB, who are now on a five-game winless streak in league matches against Cologne, paid the price for a rare lacklustre display in attack against Cologne's stoic defence.

A draw leaves Thomas Tuchel's men, who earned a fine comeback 2-2 draw at Real Madrid in the Champions League in midweek, in sixth, eight points behind rivals Bayern Munich and surprise leaders RB Leipzig, who lost to Ingolstadt.

Dortmund wasted an early chance to take the lead when Ousmane Dembele darted down the right flank and set up Reus, who slipped as he prepared to take his shot.

Cologne responded when Rudnevs shrugged off his marker on the left of the area to play in Ozcan, but the teenager rushed his shot and sent the ball high and wide.

Pierre-Emerick Aubameyang then rightly had a goal disallowed for offside, and Dortmund's misery worsened in the 28th minute. 

Jonas Hector sent in a free kick just inside Dortmund's half and Rudnevs found the net with a sublime header after winning the aerial challenge to end his side's scoring drought.

Cologne should have doubled their lead early in the second half when Yuya Osako sent Modeste clean through on goal with a superb throughball, the Frenchman rounding goalkeeper Roman Weidenfeller, only to hit the side-netting rather than the unguarded goal.

Dortmund struggled to create any chances of note in their search for an equaliser, but Reus nearly produced a moment of magic with 15 minutes left on the clock, testing Thomas Kessler with a powerful shot from a narrow angle that forced the goalkeeper into a fine save.

Tuchel's side continued to look for an opening in the closing stages of the match and they eventually made the breakthrough in the additional time.

Substitute Ramos escaped his marker's attention down the right before setting up Reus and the attacker beat Kessler with a low shot at the near post to rescue a point - his second crucial goal of the week after his previous strike versus Madrid.

There was more bad news for Cologne well into stoppage time, when Ozcan received his second yellow card of the afternoon after fouling Dembele.