Eintracht Frankfurt captain Marco Russ underwent surgery on Monday after he was diagnosed with a severe tumour disease last week.
Russ, 30, was diagnosed after a doping test had shown elevated levels of the hormone hCG, an indicator for either the use of anabolic steroids or a cancerous disease.
A medical check-up last week confirmed the disease and cleared Russ of the doping allegations, although authorities still raided his house.
Despite the news, the defender played in the first leg of Frankfurt's relegation/promotion playoff against Nurnberg last Thursday.
In the 1-1 draw with the second-tier club, Russ scored an own goal and later picked up his 10th yellow card of the season, which meant he was suspended as Frankfurt secured their top-flight status with a 1-0 second-leg win on Monday night.
The club announced on their official website that Russ had undergone surgery on the morning of the second leg and that an exact diagnosis was due later in the week.
"He texted me that he's doing well," Frankfurt coach Niko Kovac said on Sky following the 1-0 win at Nurnberg.
