Korea Republic and Manchester United were sweating Wednesday after the knee injury that kept Park Ji-Sung out of action for nine months flared again.

The winger didn't train with the Korean team on Tuesday after experiencing discomfort in his knee ahead of their FIFA World Cup™ qualifier against Turkmenistan in Ashgabat on Saturday, the Korea Times reported. Team doctors insisted it was a minor problem and nothing that couldn't be cured by a few days of rest.

But Korean manager Huh Jung-Moo and his Manchester United counterpart Alex Ferguson will be worried.

"He is not feeling pain, but the player says he is experiencing discomfort, so we are putting his knee under light rehab treatment," Korean team doctor Shin Dong-Eun was quoted as saying. He added that Park had also developed mild arthritis in the knee.

"It's not that he is injured again, but the surgically repaired knee seems to be reacting to fatigue," the doctor said. "I think he will be okay after a day's rest."

The former PSV Eindhoven star first injured the cruciate ligament in his knee during a league win against Blackburn at Old Trafford in March last year. He had to undergo career-saving surgery in the USA during the close season and only returned to action in January. Until now he had shown no ill-effects.

If he fails to recover in time for Saturday's match, West Bromwich Albion midfielder Kim Doo-hyun is likely to take his place in the free-roaming role behind the main striker. A win on Saturday will be enough to ensure South Korea make the final phase of Asian qualifying for the 2010 FIFA World Cup South Africa.