Ropati recovered from his hamstring injury to play the full 80 minutes in the following week's 30-20 victory over Brisbane, before being struck down in a heavy tackle against the Roosters.
That means Fisiiahi will make his seventh NRL appearance, and his third this season after being used at fullback for the injured Locke in April.
The 21-year-old has been in prolific try-scoring form for the Warriors' feeder side the Auckland Vulcans. He snared another hat-trick against Windsor last weekend, giving him 18 tries from just eight matches this year.
"Kevin was a chance to come back but he's still not quite right,'' Warriors coach Brian McClennan said. "We won't take any risks there so he'll have another week off. That gives Glen another opportunity in the NRL.''
Rapira, meanwhile, makes his comeback from an ankle injury and is selected on the bench in place of Ukuma Ta'ai.
Rapira, the club's most experienced front rower, will reunite last year's regular propping quartet for the first time this season, after Jacob Lillyman made a long-awaited comeback in the ninth-round won over Brisbane.
Rapira and Lillyman are both named on the bench with Ben Matulino and Russell Packer the starting front rowers. Also on the interchange is Sione Lousi, who has featured impressively in all 10 matches so far in this campaign, and Lewis Brown and Pita Godinet.
Little separates the Warriors and the Tigers. The Warriors are coming off back-to-back home wins, giving them a five win-five loss record and holding eighth spot on the ladder. The Tigers picked up two points from their bye last week and also sit on 10 points having won their last three games.
"They were under the pump there for a while and they dug themselves out and gritted their teeth and got back into the competition,'' McClennan said. "They're a very dangerous side - they've got Benji Marshall, who can be absolutely lethal and he can steer their ship around.
"We're under no illusions how tough this game's going to be. We've been a bit mixed the last four weeks, we've been good in different areas, and if we can just get it all together we'll go over there and give ourselves a good chance.''
Also helping the Warriors' chances is the absence of Tigers captain Robbie Farah, who has been selected in the New South Wales side for next week's first State of Origin match, though McClennan thought the Sydney-based side would still be dangerous without him.
"They've played without him before and did well and they still look really threatening. It probably means that Benji will step up and get the ball a little bit more.''
Warriors side to face Wests Tigers at Leichhardt Oval in Balmain on Friday night: Glen Fisiiahi, Bill Tupou, Ben Henry, Konrad Hurrell, Manu Vatuvei, James Maloney, Shaun Johnson, Russell Packer, Alehana Mara, Ben Matulino, Elijah Taylor, Simon Mannering (c), Feleti Mateo. Interchange: Lewis Brown, Sam Rapira, Sione Lousi, Jacob Lillyman, Pita Godinet.
