The 24-year-old, 123-game veteran has been selected on a bench that also includes Kiwis prop Russell Packer and Ukuma Ta'ai.
McClennan's starting line-up shows just one change from the run-on combination used against the Titans - second-rower Feleti Mateo is listed to start with Lewis Brown moving to the bench.
"It's great having Sam ready this week," McClennan said. "He was close against Gold Coast but the decision was made to give him another week."
The news on Locke isn't as positive, with McClennan saying he didn't train on Tuesday "but we're hopeful he'll pull through. We'll give him as much time as we can to recover."
Fisiiahi, who played four NRL matches last year, has scored nine tries in his last two NSW Cup matches for the Auckland Vulcans, six against Western Suburbs on March 17 and three against Manly last Saturday. In all he has 10 in four matches this season.
Named in the centres again are Jerome Ropati and Ben Henry, who combined to make 40 tackles between them last Saturday. Ropati also gained 136 metres from 14 runs, earning him the players' player of the day award from his teammates as the Warriors racked up their second win of the season, their first at home this year and the 200th in the club's history.
It was Ropati's second full 80-minute outing since his season-ending knee injury last year.
The Warriors will encounter a Roosters side at the Allianz Stadium (formerly Sydney Football Stadium) who lost 44-4 to the Storm last Sunday.
McClennan's side will go into camp in Australia after the match to prepare for another away game against Canberra on Easter Sunday.
Warriors v Roosters at Allianz Stadium, Sydney - Saturday 9.30pm
WARRIORS
1 Kevin Locke
2 Bill Tupou
3 Ben Henry
4 Jerome Ropati
5 Manu Vatuvei
6 James Maloney
7 Shaun Johnson
8 Sione Lousi
9 Nathan Friend
10 Ben Matulino
11 Feleti Mateo
12 Simon Mannering (c)
13 Elijah Taylor
Warriors: Russell Packer, Ukuma Ta'ai, Lewis Brown, Sam Rapira, Glen Fisiiahi, Konrad Hurrell.
ROOSTERS
1 Anthony Minichiello
2 Joseph 'BJ' Leilua
3 Mitchell Aubusson
4 Shaun Kenny-Dowall
5 Sam Perrett
6 Braith Anasta (c)
7 Mitchell Pearce
8 J. Waerea-Hargreaves
9 Jake Friend
10 Martin Kennedy
11 Boyd Cordner
12 Tom Symonds
13 Frank Paul Nuuausala
Roosters: Lama Tasi, Tinirau Arona, Daniel Mortimer, Mose Masoe.