Manchester United will send Rio Ferdinand for a scan on Monday in a bid to get to the bottom of the defender's troublesome back problem.
Ferdinand, 30, was expected to return to the starting line-up for Sunday's 3-0 victory over Chelsea after resuming training during the week.
Sir Alex Ferguson confirmed at his pre-match briefing on Friday that the England defender was ready to return after missing the last four games with a back spasm.
However, Ferdinand woke up on Sunday morning with a recurrence of the back pain and was not risked.
"We are sending him for another scan because we want to get to the bottom of the problem," admitted Ferguson before the game.
Jonny Evans again deputised as United closed to within five points of Liverpool.
However, the reigning champions have two games in hand on the Premier League leaders.