Union Berlin are two points ahead of their forthcoming opponents heading into the weekend's clash, having won one more match.
Match preview
Having drawn three successive league games, Koln defeated Wolfsburg 4-2 away from home last weekend.
Steffen Baumgart's side were dominant throughout, racking up 18 shots after falling behind to Lukas Nmecha's strike in only the second minute. However, Florian Kainz's penalty on the stroke of half time provided them with a two-goal cushion, which they never looked likely to throw away after the break.
In Europe, meanwhile, they secured a respectable 1-1 draw away to Nice in the Europa Conference League on Thursday, putting themselves in a strong position to progress from Group D, which also contains Partizan and FC Slovacko.
Baumgart will be aware that Sunday's test against Union Berlin may be their most difficult one of the season yet given that their forthcoming opponents are undefeated, too, but he will feel confident of avoiding defeat once again at the very least.
Indeed, Union Berlin held Bayern Munich to a 1-1 draw at Stadion An der Alten Forsterei last weekend, maintaining their unbeaten record in the process.
Sheraldo Becker's superb volley gave the hosts a 12th-minute lead, matching his best Bundesliga goalscoring tally in a season already with five goals in five matches, before Joshua Kimmich levelled the proceedings three minutes later with a deflected effort.
Both sides pushed for a winner, but in the end a share of the spoils was probably the fairest outcome, with Urs Fischer's side heading into the weekend in a Champions League qualification position having only missed out on fourth by a single point last season.
As such, they qualified for the Europa League instead, but saw their campaign kick-off with a disappointing 1-0 defeat to Union Saint-Gilloise on Thursday, with Sven Michel embodying his teammates' collective frustration by receiving a straight red card in injury-time.
Fischer will hope that his side can put their European defeat to the back of their minds and recover in Cologne on Sunday, with the Bundesliga undoubtedly taking priority for him and the club this season.
FC Koln Bundesliga form:
FC Koln form (all competitions):
Union Berlin Bundesliga form:
Union Berlin form (all competitions):
Team News
Koln made no changes to his starting XI for the trip to Nice on Thursday, and he may ask the same group of players to go again on Sunday ahead of a more winnable match against Slovacko next time out in the Europa League.
Baumgart's ability to rotate is limited by several injuries at present, with Julian Chabot, Benno Schmitz, Mathias Olesen, Dimitrios Limnios, Mark Uth and Sebastian Andersson all sidelined.
Steffen Tigges opened his account for the club against Nice and will hope to break his Bundesliga duck on Saturday.
Fischer, on the other hand, made three changes against their Belgian opponents, but still would have been surprised by his side's lacklustre performance and result.
As such, Morten Thorsby, Janik Haberer and Julian Ryerson should be restored to the starting XI, while Jordan Siebatcheu remains touch and go having missed the last two matches with a muscle strain.
Should the former Young Boys striker miss out - which would be a huge blow to Union Berlin's chances of gaining an away win - Kevin Behrens is likely to continue alongside Becker up front.
FC Koln possible starting lineup:
Schwabe; Schindler, Kilian, Hübers, Hector; Ljubicic, Skhiri; Thielmann, Duda, Kainz; Tigges
Union Berlin possible starting lineup:
Ronnow; Jaeckel, Knoche, Leite; Trimmel, Thorsby, Khedira, Haberer, Ryerson; Becker, Behrens
We say: FC Koln 1-1 Union Berlin
With both sides competing in Europe on Thursday and unlikely to want to lose their unbeaten starts to the domestic season, we can envisage a stalemate on Sunday.
These teams both prefer to counter-attack, which may produce a cagey encounter at RheinEnergieStadion.