Houllier said: 'We will decide what to do after the scan. I don't think it is major, but we will wait and see. 'If it becomes a recurring problem with him then we will bring in Diao earlier.'
Gerrard will definitely miss tonight's friendly against Lazio at Anfield but could be fit to figure in the Real Madrid centenary tournament this weekend if he is given the all-clear but the return of his old stop-start schedule is a worry.
Houllier yesterday completed his fifth summer signing by snapping up French goalkeeper Patrice Luzi from Monaco on a free transfer. Luzi, 21, will be fourth choice behind Jerzy Dudek, Chris Kirkland and Pegguy Arphexad.