German football authorities have been told to find a compromise with the visiting China Under-20 team over the issue of pro-Tibet protests, or scrap their remaining friendlies.
The Chinese junior team is touring southwest Germany as part of an initiative aimed at advancing China's chances at the 2020 Olympics in Tokyo.
Angela Merkel's German government signed a agreement governing football with the Chinese last year, but the Under-20 project has become a diplomatic headache.
The Chinese juniors walked off the pitch in Mainz last Saturday after a group of spectators flew Tibetan flags during the first of 16 planned friendlies against German fourth division clubs.
With the match televised live in China, FSV Schott Mainz won 3-0.
However, the Chinese only agreed to play on following a 25-minute delay after 'Tibet Initiative Germany' activists were persuaded to take down the offending flags.
Till Pleuger, Schott's general manager, says a compromise must be found or the friendlies, which are planned until next May, must be scrapped.
"The DFB (German football association) has to sit down with the Chinese and talk," Pleuger told Die Welt newspaper.
"They have to find an amicable solution, and if that's not possible, then the whole thing has to be broken off in the interests of all parties.
"I do not understand the Chinese response."
More disruption is possible this weekend with fans of FSV Frankfurt, whom the Chinese face next, planning a protest for the match on Saturday.
"I know that our fans have registered a banner pointing out freedom of expression in Germany and they also want to hang up a Tibetan flag," FSV Frankfurt's president Michael Goerner told local TV.
The club's position on the issue is clear.
"We do not deviate an inch from the basic rights of our democracy, which includes the freedom of expression," Goerner said in an interview with two Stuttgart-based papers.
After the fiasco in Mainz, Ronny Zimmermann, the DFB's vice president, said it would seek talks with the Chinese in the hope that the Asian visitors react "more calmly" to future protests.
However, foreign ministry spokesman Lu Kang said on Monday that China's government was "firmly opposed to any country or any individual offering support to separatist, anti-China and terrorist activities or activities defending Tibet independence, in any form or under any pretext."
China has ruled Tibet since the 1950s, and has been accused of trying to eradicate its Buddhist-based culture through political and religious repression.
Beijing insists that Tibetans enjoy extensive freedoms and that it has brought economic growth to the region.