Early career Born to a German father and a Serbian mother, Rensing joined Bayern in 2000 from TuS Lingen, and went on to develop his talent in the club's youth sides. He made two appearances for the
reserve side in the
2001–02 season and spending the
2002–03 season in the
Regionalliga Süd, making 34 league appearances and a cup appearance, and won a place in the UEFA Champions League squad at the start of the following campaign as he moved up the Bayern pecking order to become
Oliver Kahn's deputy.
Bayern Munich in 2006 Rensing made his Bundesliga debut on 21 February 2004, playing the entire 90 minutes of the 1–0 home win against
Hamburger SV. He also made an appearance against
Schalke 04. Rensing saw action in four Bundesliga matches and two cup matches in
2004–05 season and saw his first
Champions League nod for an injured
Oliver Kahn against
Milan on 21 February 2006 (Milan keeper
Dida was injured during the match, so both sides finished with reserve goalkeepers in goal), which ended in a 1–1 draw. On 15 April 2006, Rensing was involved in a strange incident prior to a match against
Arminia Bielefeld. He took a warm-up shot that struck goalkeeper
Oliver Kahn blackening his eye and forcing him to sit out the game. Rensing played in Kahn's place and Bayern went on to win the contest 2–0. In the
2006–07 season, he made a Bundesliga appearance against
Borussia Mönchengladbach, two cup appearances, and a Champions League match against Milan. once in the Cup, Following a poor start to the 2009–10 season, his experienced teammate
Hans-Jörg Butt replaced him as the Bavarian club's first-choice goalkeeper. Rensing had played on matchdays one, two, and three. Although Rensing made a half-time substitute appearance for the unwell Butt in a 3–2 win at
Werder Bremen on 23 January 2010 and made three appearances in the DFB-Pokal, but rejected the subsequent contract offer.
1. FC Köln On 21 December 2010, Rensing moved to
1. FC Köln on a six-month contract. He made 17 league appearances in the
2010–11 season. Following his half-season at
1. FC Köln, Rensing was voted the No.3 keeper in Germany by
kicker sports magazine. Due to his strong performance, Rensing's contract with
1. FC Köln was extended two years to 2013. He made 32 league appearances and an appearance in the Cup during the
2011–12 season. However, he was released by Köln upon the club's relegation in 2012. He finished his Köln career with 49 league appearances.
Fortuna Düsseldorf Since 1 July 2013, Rensing has played for
Fortuna Düsseldorf. Before the first match of the season Rensing stormed out of training and was thus dropped from the team for that match. The argument was concerning
Fabian Giefer being selected as first-choice keeper above him. Because of this he was told that he would not be picked for league games due to his "childish reaction" over the incident. He ended up playing in five matches during the
2013–14 season. In the
2014–15 season, Rensing has played in 12 of the first 13 games of the season in the 2. Bundesliga, and has also played in the single DFB-Pokal game. He finished the season with 24 league matches played. with the exception of the first round cup match against
Rot Weiss Essen where
Lars Unnerstall played. Rensing finished the
2016–17 season with 34 league appearances and two cup appearances. Rensing started the
2017–18 season by starting the first three league matches and the opening round of the German Cup. Rensing picked up an injury against 1. FC Kaiserslautern. ==International career==