Coachloads of police were deployed Tuesday for a Japanese football club's match in Nanjing, scene of the worst atrocities of Japan's 1930s invasion of China, which still weighs heavily on ties.
Beijing and Tokyo are embroiled in a bitter dispute over islands in the East China Sea, and tensions are expected to be high on the pitch for the AFC Champions League game between Japan's Vegalta Sendai and home side Jiangsu Sainty.
Last season's Chinese Super League runners-up have offered their players a huge bonus pool of four million yuan ($640,000) if they beat the J-League team, a club official confirmed to AFP.
Beyond the result, many are attaching huge symbolic importance to what is thought to be the first senior men's football match involving a Japanese team in Nanjing, where invading troops launched a brutal massacre in 1937.
"The players have privately said 'We all know the significance of facing a Japanese team at home in Nanjing'," said the jiangsu.china.com website, the online mouthpiece of the local government.
The relationship between the two countries is still deeply strained by Japan's bloody wartime occupation, including the Nanjing Massacre in which 300,000 civilians and soldiers died, according to China.
Some foreign academics estimate a significantly lower death toll.
In the weeks running up to the game Chinese media reported there were plans to move it from the 60,000-seater Nanjing Olympic Sports Centre to another location in the eastern province of Jiangsu.
"I don't know why the Japanese have to come here to play football," a woman surnamed Lu told AFP as she waited at one of Nanjing's busy train stations on the afternoon before the match.
"I don't even like football, but everyone in Nanjing knows about this game."
Four hours before kick-off, police lined up in rows outside the stadium as Jiangsu Sainty fans waved flags and banners.
One Chinese report said Japan had asked China to guarantee the safety of the visiting team and its supporters in the city.
Another said Chinese authorities had urged the Japanese fans to use only designated buses to travel to the stadium, and asked visiting Japanese media to stay at the team hotel.
Reports in Japan also say fans attending the match have been warned to keep a low profile.
Up to 13,000 police and security were estimated to have been in place last month when Chinese champions Guangzhou Evergrande hosted Urawa Red Diamonds, one of Japan's most decorated clubs, in the pan-Asian competition.
Some media reported that the Jiangsu game would see even tighter security, but police in Nanjing would not comment on numbers when contacted by AFP.
Police were carrying out strict searches coming into the area of the ground and banned cars from the immediate area.
Only a small number of Japanese fans were expected, with about 100 tickets sold through the club and a travel agent, although more may try to gain entry at the stadium.
On its website, the Japanese embassy in Beijing posted safety advice for fans travelling to China for Wednesday's clash between Beijing Guoan and Japan's Sanfrecce Hiroshima.
It pointed out that "anti-Japan demonstrations and other activities" happened in China last year amid the islands row, adding: "It is still necessary at present to be careful by refraining from speaking in Japanese in the streets or otherwise making yourself highly visible."
"Please be careful about what you say or do in China inside or outside the match venue, bearing in mind the recent situation," it said.
"When you cheer in the match, please cheer in a good manner without excessively jeering opposing players or supporters, or acting in a way that insults the opposing country."