Pivac moved to sign Collins - who was born in New Zealand, but is Welsh-qualified through his grandmother - with full-back Liam Williams and centre Scott Williams set for extended spells on the sidelines due to foot and knee injuries respectively.
But Pivac is content Collins can become an asset to Scarlets in the Wales international pair's absence as the team bids to continue their 100 per cent record.
"He kicks off both feet and has a good skill set, so I think he will be invaluable for us," Pivac told the South Wales Evening Post.
"When we get to Europe and the 6 Nations there's going to be a lot of rugby played.
"With those two out it was imperative that we tried to fill at least one of those positions.
"Michael's name has been mentioned in the past through an agency.
"He is Welsh-qualified and we've being going through a process of looking at Welsh-qualified players from outside Wales in case of a situation like this.
"An ongoing relationship with agents sometimes pays off.
"The game's evolved. The agents have a lot of information so it would be silly not to be using them."
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