Two penalties in the final minutes of the match saw winless Cologne capitulate as they threw away a 3-0 lead to lose 4-3 at home to Freiburg.
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Freiburg and Hamburg battled out an uninspiring goalless draw on Friday night which did little to boost either side's position in the Bundesliga.
Hamburg have been granted special dispensation from the authorities to play 17-year-old striker Jann-Fiete Arp in the Bundesliga on Friday.
Bayern Munich marked the return of veteran coach Jupp Heynckes with an emphatic 5-0 win over Freiburg.
Ten-man Freiburg halted Borussia Dortmund's promising start to the season Saturday in a 0-0 Bundesliga draw and also added to the team's injury list.
Allan, 20, joined Liverpool in 2015 and was on loan at German club Hertha Berlin last season.
Freiburg have confirmed the signing of Philipp Lienhart from Real Madrid on a one-year loan deal with a view to a permanent move.
Lienhart, 20, has been a regular for Madrid's Castilla youth side since joining from Rapid Vienna in 2015.
Germany under-21 international Philipp, 23, has signed a five-year deal for a reported fee of up to €20 million.
Performance on Saturday was part of choreographed celebrations of Bayern's fifth successive Bundesliga title.
Philipp Lahm and Xabi Alonso received standing ovations as Bayern Munich sent two of modern football's maestros into retirement on a winning note.
Borussia Dortmund overcame a traumatic week to retain fourth place in the Bundesliga by toppling Eintracht Frankfurt 3-1.
Bayern Munich continued their Bundesliga dominance as they beat Eintracht Frankfurt 3-0 on Saturday.
Borussia Dortmund won away from home for only the second time in the Bundesliga since November to stay in third place with a 3-0 win at Freiburg.
Robert Lewandowski scored an injury-time equaliser as Bayern Munich salvaged a 1-1 draw away to Hertha Berlin.
Bayern Munich were held to a 1-1 draw at home by Schalke as the Bundesliga leaders laboured to another unconvincing display on Saturday.
Borussia Dortmund conceded a late equaliser to Dortmund to further dent their fading title hopes, while Freiburg beat Hertha Berlin at home.
Robert Lewandowski's late winner helped Bayern Munich see off a game Freiburg squad to start the 2017 portion of their campaign with a 2-1 victory.
Returning from a month-long break, league leaders Bayern Munich need to be wary of a trip to Freiburg, a place that has caused them problems of late.