Owen Farrell will be given until Friday to prove his fitness for Saracens' Champions Cup quarter-final against Leinster but Billy Vunipola has been ruled out of the trip to Dublin.
Farrell is struggling with a quad injury he suffered in England's final NatWest 6 Nations match against Ireland and only returned to light training on Wednesday with Alex Lozowski on standby to deputise.
Vunipola had been pencilled in to make his comeback from the fractured arm sustained in January at the Aviva Stadium on Sunday but remains a couple of weeks away from full fitness.
"We'll make a decision on Owen on Friday. His chances are probably 50-50. Billy won't be available," Saracens director of rugby Mark McCall said.
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