Davies sustained a knee injury in the GUINNESS PRO12 victory against the Newport Gwent Dragons at the start of October and will be unavailable for up to three months.
Davies was the top try scorer in the league last season and with Scarlets turning their attentions to Europe they will need the likes of Rhodri Williams and Aled Davies to step up to the plate.
Davies' injury also comes at a bad time when Warren Gatland is picking his squad for Wales' autumn internationals and Pivac admits his side must learn to cope with injuries to their front-line stars.
"Gareth is a strong player for us and last season he was the league's top try scorer," he said.
"Along with Ken Owens and Regan King, they are three front line players who have been missing for us.
"All those players for us are a blow. But we have to focus on the guys who are available and make sure we put our best foot forward."
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