The star Australian allrounder's brilliant spin control, taking 2-10 off her 20 balls including the key wicket of Meg Lanning, eventually proved enough to pave the way for the Rockets' six-wicket win at the London home of the Oval Invincibles on Thursday.
It was only the Nottingham-based side's second win of the campaign and still may not be enough to help them edge their way into the playoffs.
But, ultimately, the skipper was relieved they're still in the tournament at all after she gave away her wicket cheaply while the Rockets attempted to chase down the Invincibles' modest 7-109.
With the chase seemingly under control and having just struck a couple of sweet boundaries, Gardner holed out inexplicably to long-on for 11 off the tricky spin of her compatriot Amanda Jade Wellington (1-15) to suddenly plunge her side into a dog-fight.
Clearly mad with herself, she had head gloomily in hands in the dugout, knowing defeat would eliminate the Rockets, which looked a distinct possibility when they then slipped to 4-75.
But a cool unbroken partnership between another Australian international Heather Graham (19no off 11 balls, including a six and two fours) and Jodi Grewcock (21no off 14) took the Rockets to victory with 16 balls to spare.
Lanning, Australia's greatest women's captain who's enjoying a pressure-free spell without the skipper's armband for the Invincibles, had been fuming at herself too earlier when she looked to be guiding the home side to a decent total.
Going well on 45 off 35 balls, featuring one six and six fours, Lanning, the competition's top-scorer with 247 runs, looked disgusted when she tried to clear the ropes off Gardner, only to get caught at long-on by England international Nat Sciver-Brunt.
Straight after, Gardner also captured the other key batter, South African star Marizanne Kapp, who chipped one straight back to her for a soft caught and bowled.
Wily Aussie legspinner Alana King then got in on the act, having Wellington stumped off her legspin. Graham, who had a fine allround game, also chipped in with a wicket (1-27).
Both the Rockets and the Invincibles must now win their remaining two matches and hope results go in their favour elsewhere to finish in the top-three in the group stage.
