A scan on the defender’s dislocated shoulder revealed no significant damage, but the 24-year-old is still likely to be missing for a couple of weeks.
Gretarsson suffered the injury during Blackpool’s 1-0 win against Sunderland last weekend, when he also picked up a dead leg.
Jordan Thorniley took his spot during Tuesday night’s game at Rochdale, but the Seasiders also have James Husband and Marvin Ekpiteta waiting in the wings following their recent returns.
“We have got options in that area of the pitch at this moment in time,” Critchley said.
“I remember a couple of incidents this season where we’ve made a decision and then a week down the line or two weeks down the line, someone gets sent off, suspended or injured and you’re thinking ‘I wish we had done something different’.
“We’ll do the right thing by Daniel, that’s the most important thing, to always do the right thing by the player.
“A little bit of patience will help us make the right decision for him and for us in the long term.”
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