Adelaide Strikers 5 for 113 (Penna 56*) beat Melbourne Stars 8 for 112 (Wellington 3-20) by five wickets
Chasing 113 at Lilac Hill, Strikers were 3 for 18 when Deandra Dottin, Katie Mack and Laura Wolvaardt all fell.
Penna (56 not out from 50 balls) and Bridget Patterson (31 off 33) put on 44 to stop the rot before Penna kicked on to see Strikers home with five balls to spare.
She latched onto one pull shot for a timely six and drove well, bucking the trend on a day dominated by bowlers to embed Strikers in the top four. Incredibly, it was the third time Penna had scored 56, her highest WBBL total.
Earlier Annabel Sutherland played a lone hand with the bat for Stars, her 41-ball 47 coming while Megan Schutt and Amanda-Jade Wellington had tormented her team-mates.
Sutherland also took 2 for 19 from her four overs, but her solo efforts weren't enough for Stars