Genia spent six months on the sidelines after suffering a serious knee injury against South Africa last year and applied ice to the knee after the second test, stoking fears about his fitness ahead of the series decider in Sydney.
"It's obviously part of the history," Deans told reporters.
"He tweaked it a couple of weeks back, nothing major, but obviously any management he does on it is very visible.
"But he's managing it fine. There's no structural issues ... Once he gets out and gets going it's not an issue.
"And he is managing it, which is progress for Willy because he doesn't like slowing up whether it be preparations or in-game."
The loss of Genia would be a hammer blow to the Wallabies, who have relied on the playmaker's creativity and poise to set up scoring chances in both the attritional tests.
Genia was at his canny best in Brisbane, setting up the first of winger Israel Folau's two tries, and carried the form into Melbourne's Docklands Stadium to help the Wallabies level the series 1-1.
In contrast to the carnage at Lang Park, when three Wallabies backs were carried off, Deans said the side had emerged from the second test largely unscathed.
Adam Ashley-Cooper suffered a knee injury but Deans said the centre was optimistic to play in Sydney though his self-diagnosis was "not really scientific".
"There's possibly a bit of soft tissue niggle from a couple of blokes," Deans said.
"It was a typical changing room, there was a lot of ice around and a lot of tired bodies, but I think to the greater extent we came through it unscathed."
Local media have speculated that New Zealander Deans, never fully embraced by the Australian public, is playing for his coaching future, with his contract set to expire at the end of the season.
Handing the Lions their first series win in 16 years would heap pressure on the Australian Rugby Union to end his tenure and hand the role to outgoing Queensland Reds coach Ewen McKenzie or the ACT Brumbies' World Cup-winning mentor Jake White.
"Fatigue is a big part of it," Deans said when asked about his feelings the morning after the Wallabies' fighting win.
"Which obviously reflects the emotion, I guess.
"The boys had to work very hard for that result. It was obviously a demanding week.
"As I said last night, proud of the way the guys found a way to win which obviously was important in the context of the series."
While it was fly-half James O'Connor and Kurtley Beale leaving points on the tee at Lang Park, the Wallabies backs were again culpable in botching scoring chances with a rash of handling errors and poor decision-making in the second half.
O'Connor, a contentious choice at fly-half before the series, improved as the match progressed and fed Ashley-Cooper for the winning try, but the Wallabies largely struggled to work through phases and hold onto possession.
"There were times where we relieved the pressure where we had them on the back foot," O'Connor said of the backline, which featured three players in Folau, winger Joe Tomane and inside centre Christian Lealiifano playing only their second tests.
Deans said he would persist with the raw backline for the Sydney decider and O'Connor thought they were gradually working each other out.
"The more you play with the team, the tighter the bonds become and the better connections you get with the guys playing around you," he said.
"Guys like Izzy (Folau), Joe and Christian were all pumped for this test in Sydney, we know how much we left out there on the field and how much more we can bring as a team."
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