[TAREK®]

United were dealt mixed news on the injury front this weekend when no sooner had Antonio Valencia started training with the Reserves after a five-month injury lay-off than Ji-sung Park was ruled out for four weeks with a hamstring injury.

Park had only last week begun training with the rest of the squad again after returning from a month-long involvement with South Korea at the Asian Cup in Qatar, after which he announced his retirement from international football.

The Korean midfielder has been a key player for United this season, particularly in Valencia's absence, and Sir Alex had been looking forward to welcoming him back into the first-team fold.

"We got a blow on Saturday morning with the news that Ji-sung Park did his hamstring on Friday afternoon in training," the boss explained to ManUtd.com. "It was very unfortunate because it was his last kick of the ball in training as well. We were really looking forward to having him back after being away for a month at the Asian Cup. He’ll be out for up to a month, which is a blow to us."

On a more positive note, fellow winger Valencia is edging ever closer to a return after breaking his ankle and suffering ligament damage in an innocuous challenge during United's 0-0 Champions League draw with Rangers at Old Trafford in September.

"The good news is that Valencia started training with the Reserves on Saturday," added the boss. "So he’s on his way back and that will be a real boost to have him available for the run-in."

It was initially feared he might miss the entire season. But after undergoing an operation he has worked hard during the rehabilitation process and the indication is that he could play again in March.