|Pro14: Ulster v Scarlets|
|Venue: Kingspan Stadium, Belfast Date: Friday, 15 September Kick-off: 19:35 BST|
|Coverage: Live BBC Two Wales, BBC NI and online and the BBC Sport app, highlights later online and Scrum V on BBC Two Wales on Sunday from 18:00 BST|
Jonathan Davies and Ken Owens will make their first appearances of the season when Scarlets face Ulster in Belfast.
The British and Irish Lions pair missed the first two Pro14 matches of the season but captain Owens starts with Davies on the bench.
Neither player has played since the Lions drew the third Test against New Zealand in Eden Park on 8 July to earn a 1-1 draw in the series.
Davies was voted the Lions' player of the series by the tourists.
Champions Scarlets also include Wales internationals Leigh Halfpenny and lock Jake Ball, who both missed last weekend's bonus-point win over Zebre.
Pivac says he is not concerned that the return of the Lions players will disrupt the side who have won their past 10 matches in the tournament.
"That's why Leigh (Halfpenny) came back a bit earlier," added Pivac.
"It's kind of a drip-feed and we did it really well after the Six Nations last season and it worked well for us.
"We brought some boys straight in and the others had two weeks off.
"And the boys who came straight in had two weeks off down the track and we swapped it around a bit.
"Jon in particular has needed a big break because he's played a lot of rugby, in that Lions series he played every minute of it so he deserved a break, which he had.
"Ken too, he came off a foot injury and went on a Lions tour and was involved in every Test.
"They've had a good break now and were introduced into training a few weeks back so it's not like they are coming back one day and then straight into the team."
Pivac added both players had played in second-string teams in training in the build-up to their returns.
The New Zealander conceded Friday's match at Kingspan Stadium was going to be the Scarlets' toughest test since winning the final Pro12 title by beating Munster in May.
"Ulster is definitely a step up," he added.
"Two unbeaten teams and we've got the utmost respect for Ulster, they've got quality throughout their team."
Ulster are without star scrum-half Charles Piutau and lock Marcell Coetzee, who are both injured.