France striker Djibril Cisse suffered a broken leg after a challenge from China's Zheng Zhi in a warm-up match for the 2006 World Cup, ruling the former Liverpool striker out of the finals.
"There are so many superstars in the Portuguese team, especially Cristiano Ronaldo. We didn't want to see a repeat of the Cisse tragedy. We don't want a World Cup without Cristiano Ronaldo because of our fault," Gao told Chinese media.
"We played conservatively on the pitch because our players wanted to hurt neither themselves nor the Portuguese players." China, who have qualified for the World Cup just once, will not be going to South Africa having fallen at the first hurdle in Asian qualifying two years ago.
Although an ongoing match-fixing scandal has only made Chinese football's already miserable reputation worse, Gao's team gave it a surprise boost when they won the East Asian championship last month.
"From this year on, Team China will not be satisfied by just playing Asian teams. We will upgrade our opponents in friendlies," Gao, whose team are 83rd in the FIFA world rankings, told the Soccer News.
