After failing to earn a point against the Bulls, the Blues are not surprisingly extremely keen to finish their South African tour with a victory over a Lions team that has already shocked the Cheetahs and Stormers this season.
Marshall comes in for Charles Piutau, with the new All Black, the Blues' most elusive and dangerous back this season, moved to the left wing in place of Tevita Li. Pita Ahki replaces Jackson Willison at second-five, with George Moala retaining his position at centre.
Referring to 20-year-old Hickey's demotion, Kirwan said: "Simon has done absolutely nothing wrong. We're trying to create competition. Also, Tevita and Simon especially, we're aware of their young training age."
A potential side effect of Kirwan continually changing his side is that players, apart from senior operators such as prop Tony Woodcock and skipper Luke Braid, have higher stress levels and are unwilling to take as many risks. One of Kirwan's team's strengths is their creativity and flair on the counter-attack. He will hope there is more of that against the Lions than there was last weekend against a Bulls team which were far too strong defensively.
A better start is also imperative. The Blues' tendency to give away leads has become worrying already this season.
Kirwan said he also wanted improvements at the breakdown in what are likely to be more wet conditions. The rain has hardly stopped falling on the Blues on this trip and more is expected on Sunday morning.
Marshall's start at fullback comes after Kirwan stated before the season that the former league player was concentrating only on first-five. A late cameo at fullback against the Highlanders was followed by a bench role only against the Crusaders and he wasn't required in the match-day squad at Loftus Versfeld.
Marshall conceded it had been a challenging few weeks.
"It's been a tough couple of weeks patience-wise," Marshall said. "It's a bit of the other side of the coin for me. I'm used to being in a starting line-up in league and then coming back and having to be a bit more patient, not getting on against the Crusaders and then not being in the team the week after, so to get the opportunity to start, you've just got to take your opportunities."