SAPPORO, Japan, Aug 18 - China's Yao Ming said on Friday he was frustrated that his injured left foot was taking so long to heal completely.

The 7ft-5in Houston Rockets centre also lamented his lack of stamina on the eve of China's opening game of the world basketball championship against Italy.

"The injury seems to be taking a long time to clear up," Yao told reporters after practice in Sapporo. "I am obviously not yet anywhere near my best form and stamina is still a problem."

Yao broke his foot in an NBA game in April and China performed abysmally in his absence in a series of warm-up events before coming to Japan for the world championship.

However, Yao expressed confidence that China, drawn with the United States, Italy, Slovenia, Senegal and Puerto Rico in Group D, would qualify for the last 16.

"Italy will be a tough game to start with. They got to the (2004) Olympic final so they're obviously very strong," he said.

"They have dangerous outside shooters too so we will have to work out a plan to shut them down. I still feel confident that we can get into the last 16."

The top four teams from the four six-team groups advance to the knockout stages, which begin in Saitama on August 26. The final takes place on September 3.