One intended change has already been scrubbed, with fullback Kevin Locke today (Thurs) ruled out for a third week with a cork above his right knee and his place in the side has been taken by the mercurial Krisnan Inu.
Inu is a proven matchwinner - he scored the winning try against Wests Tigers last season as the Warriors marched to the grand final - but his attitude and work ethic are often called into question. He played against the Eels earlier in the season but has had to be content with a place in the Auckland Vulcans side for most of the season.
McClennan has also made some changes at training in an effort to find the right formula.
"We freshened up training," he said. "It's still very intense but shorter and sharper. That's been the main focus this week. Short and sharp and to the point. We have freshened the guys up so we can go onto the field on Sunday against the Rabbitohs nice and bouncy and ready to play.
"We have spoken a lot about having a really tough attitude. The last couple of weeks, our mental toughness and attitude in the game haven't been up to the mark."
It has highlighted the number of inexperienced players in the side. Centres Ben Henry and Konrad Hurrell are in their debut seasons, and prop Sione Louisi, halfback Shaun Johnson and back-rower Elijah Taylor still haven't notched 30 games.
They are clearly missing the experience and grit of Micheal Luck and Jacob Lillyman, who have both been unsighted this season, and teams have exposed the Warriors' frailties on defence down both flanks.
Sunday's match against the Rabbitohs is an important one to ease some pressure on the club and lift them on the table but they are also mindful of the fact they have games against Melbourne (A) and the Broncos (H) to follow.
"This game is very important," McClennan said. "Souths have won their last two and have got a confidence booster. They are a team on the rise.
"The top teams are Melbourne by some way and then Brisbane, who are playing good footy, too. It's a tough run on the horizon. But I think that's good. I think that's what we need to lift our game right up. That starts on Sunday.
"It's important for ourselves first and foremost to have a really good performance and it's important to us that we put in a performance that all Warriors supporters fell proud of. At the moment, we have been letting ourselves down and everyone else down."