An important encounter at the Alten-Försterei for FCK, who headed into the game knowing that bettering Darmstadt's result would land them in the top two as we head towards the business end of the season.
Union headed into the game in 11th place, with a form of WLWLW, meaning it should be a tough test for Kaiserslautern at a packed stadium in the Berlin forest.
It was the home side who started the game brighter, with a couple of shots from the edge of the box going well over the bar inside the opening three minutes.
There was a chance to break the deadlock in the 19th minute as Björn Jopek was given the ball in space on the edge of the box. He chose to dart towards goal but was well cut out before he could pull the trigger, and the ball trickled into the greatful arms of Sippel.
It was a real territorial battle in midfield during the first half, and referee Florian Meyer did his bit in preserving the flow of the game, while Parensen and Kreilach engaged in battles with Karl, Hofmann and Matmour.
In the 34th minute the visitors had a half chance, as a ball was headed back into the box before falling to Ring, who drilled the ball well over from 18 yards out.
Löwe delivered a dangerous set piece from the right side in the 36th minute, but it drifted past everyone and about a foot wide of the far post.
The teams went in at the break still locked at 0-0, without any clear opportunities for either side to take the lead. Kaiserslautern got into the game with periods of pressure, but there was nothing near an end product from either side. A total of nine shots in the opening 45 minutes, with zero on target, telling the story of the first half.
Kaiserslautern had the first chance of the second half when Union failed to clear, and the ball sat up perfectly for Matmour to hit a sweet half volley. Luckily, Amsif was in position to save comfortably and keep the score 0-0, but it was the first shot on target recorded by either side.
On the hour mark Kreilach went into the book for a foul on the edge of the box which provided a good set piece opportunity for FCK, but Ring hit the effort tamely straight at the 'keeper.
There was an unfortunate piece of timing in the 69th minute, as the newly introduced Kobylanski burst inside from the left before unleashing a powerful drive that hit Polter so hard it knocked him to the ground, and he was in an offside position so the play was blown dead.
Two minutes later Matmour had a volley for FCK that was heading the the left corner, but Amsif did well to dive and hold onto the ball.
Polter went to ground inside the box in the 78th minute under a 'challenge' from Orban, but it was clear simulation as the desperation of both sides was becoming apparent.
In the final chance of the game with seconds to go, Ring collected a low cross from Stöger and hit it goalwards, but it was saved again by Amsif.
The referee blew the whistle and the game ended 0-0, a fair reflection on the scrappy and even nature of the game. The visitors certainly had the better of the chances, but ultimately never really looked like scoring, which is a positive for Union.
Union dropped to 12th as Sandhausen won again, while FCK missed out on Darmstadt dropping points, remaining in third place.