Aston Villa midfielder Stephen Ireland is sidelined with a knee injury which will keep him out of action for at least another week.
Ireland has struggled to make an impact since his Â£8 million summer move to Villa as part of the deal which saw James Milner head in the opposite direction to Manchester City.
He was encouraged to "work harder" early in Houllier's reign and has not played since the 3-0 defeat at Liverpool in early December. Now it has emerged Ireland has been ruled out for the past fortnight with the knee setback suffered in training which also rules him out of contention for Sunday's Birmingham derby.
Houllier confirmed: "Stephen Ireland has a knee injury. He has been out for two to three weeks now, I think.
"It's a ligament. It will probably be another week (out of action) but he can't train yet."
Houllier has received more encouraging news regarding right-back Luke Young, who has returned to training after recovering from his knee problem.
The Villa boss said: "Luke Young has just got back from his injury.
"He returned to training with the first team for the first time yesterday (Friday)."
Young may face a battle to regain his place as Houllier has signed Tottenham's Kyle Walker on loan for the remainder of the season.