Leighton Baines will miss Saturday's trip to Burnley after suffering a setback with his recent hamstring injury.
The Blues left-back has not featured since last month's 3-1 home win against Middlesbrough and, at his press conference on Thursday, boss Ronald Koeman confirmed the defender would not be in his matchday squad for the clash at Turf Moor.
Koeman said: “It is difficult because Leighton did the normal programme to come back - he had good sessions and played 45 minutes in a behind-closed-doors game against Wigan.
“But then the day after he was a little bit stiff and he went for a scan that showed he had a little setback.
“It is tricky. Maybe we need to wait longer to get him back to 100 per cent. It is difficult to say how long it will take but we will see.”
Aaron Lennon, meanwhile, has shaken off a knock and is available for selection after missing last weekend’s 1-1 draw against Manchester City.
Long-term absentees Muhamed Besic, Tyias Browning (both knee) and Matthew Pennington (hamstring) remain unavailable.