The first Chinese man to hold a world swimming record in the modern era, Zhang Lin, Beijing 2008 medallist over 400m freestyle, may have fallen shy of best in a fourth-place finish at nationals in Shaoxing because he suffered an asthma attack.

Coach Chen Yinghong cited the condition when explaining how 25-year-old Zhang, winner of the men's 800m freestyle at 2009 Rome world titles in a world record at a time of shiny suits now banned, came to clock 3:49.14 in the 400m yesterday, 0.22sec shy of FINA A cut for London 2012, when much more was expected.

Teenagers Hao Yun and Li Yunqi are now ahead of the Beijing 2008 home hero in the line to make the 400m selection.

"It's weird," Chen told Xinhua. "According to his physical conditions, I think the poor result is probably caused by his asthma. He has been dealing with it in the past year. The asthma attacks had happened two or three times during his training and affected the results."

"I had expected that he could swim within 3:42 or 3:43 in the final, but the result was surprisingly bad," Chen added. "He told me that he felt stuffy and a little out of breath before the heats earlier Tuesday and didn't feel good before the final either, but I didn't think about the asthma at that time and just gave him some encouragement."

The coach continued: "Zhang could swim within 3:50 even with a shoulder injury when trained in America, and he is in good condition recently. Even if he had not taken part in competition for a long time, the result should not be so bad. We thought about the reason the whole night, and the only explanation is his asthma."

Zhang suffered an asthma attack in the 1,500m free final at Rome 2009 world titles and has been managing the condition since, in common with a large percentage of world-class swimmers, who must register as asthmatics to avoid problems with anti-doping controls that can top a result the wrong way depending on dosage of treatment.

Chen noted that Zhang had been upset by the 400m result yesterday. "We had a long talk today," said the coach. "Now Zhang will focus on the following competitions and try his best to qualify for the London Games. His training is good, and if he can perform his normal level, he's still hopeful in the 200m free."