Sunderland defender Wes Brown was heading back to Wearside on Monday fearing yet another lengthy injury lay-off.
The 32-year-old former Manchester United player limped off during the first half of Sunday's 3-2 Peace Cup victory over FC Groningen in Korea with suspected knee ligament damage.
With summer signing Carlos Cueller having already left the pitch with a thigh problem and both Phil Bardsley and Matt Kilgallon not fit enough to make the trip, Black Cats boss Martin O'Neill's defensive problems appear to be mounting. O'Neill told the Sunderland Echo: "Wes is the worry. It could be a bad one, but we really don't know at this stage."
He went on: "You are told one thing at half-time and another thing at full-time, so really, it's too early to tell. We will probably only find out once we are home and it settles down, but hopefully it won't be too bad because he's an important player for us."
Brown arrived at the Stadium of Light last summer from Old Trafford, where injuries had repeatedly hampered him, but started each of the first 20 games of the new campaign.
A groin strain suffered in a 1-0 Barclays Premier League victory over Manchester City on New Year's Day saw him sit out three games, but it was a knee injury sustained in an FA Cup fourth round tie against Middlesbrough on January 29 which effectively ended his season. Cuellar, 30, is less of a concern, and his premature departure was more precautionary.
The Ulsterman will hope to step up his recruitment drive on his return - former Aston Villa defender Cuellar is his only new acquisition to date - with attacking players his priority.
Reports over the weekend suggested he had returned to Villa to snap up Stephen Warnock and James Collins, but while maintaining his stance of refusing to talk about specific players, O'Neill hinted he is currently concentrating on a different set of targets.
He said: "Undoubtedly, what is focusing my mind more than anything else is the need to strengthen our attacking options. We have lost Nicklas Bendtner after his loan, we have lost Asamoah Gyan from our squad list and we need to bring in strikers.
"What I am looking to do is bring in attacking players who have quality and who have more experience than we have now, because, when you look at our squad in terms of attackers, we are short on experience and it's something we need to try to address."