Kapp starred in the field as the Stars easily beat top-side Hobart by 37 runs on Thursday at Junction Oval.
Their third-straight win left the Stars second on the ladder ahead of Saturday's massive home derby against the third-placed Renegades.
While teammate Amy Jones was player of the match, Kapp went all Mitchell Starc and bowled Lizelle Lee with the first delivery of the Hurricanes innings.
She removed fellow opener Danielle Wyatt-Hodge in the third over and took an outstanding catch to remove No.4 Nicola Carey.
But Saturday's match will be the last for Kapp before she returns to the South African team.
"Obviously Kappy is going to be a massive loss - it seems like she's playing her best cricket, now that she's leaving us, which is a bit frustrating," teammate Kim Garth said.
"But I feel like we do have the depth to cover it."
Garth added they were worried about what damage Lee could do.
"I was pretty relieved - she was hitting them pretty well," Garth said.
"We did a lot of planning for her and when Kappy comes in and knocks her over first ball, it's quite nice."
After starting the season with five-straight wins, the Hurricanes have lost their last two and are in danger of ceding top spot to either Melbourne team.
The Renegades will host Perth on Thursday ahead of Saturday's clash against the Stars, who are only one point behind the Hurricanes.
After Hobart won the toss on Wednesday at Junction Oval, Jones and Danielle Gibson gave momentum to Melbourne's stalled innings and the home side reached 6-151 from their 20 overs.
The Hurricanes were bundled out for 114 with 22 deliveries left.
Jones top-scored with 59 from 40 balls, featuring six fours and a six.
Jones and Gibson came together at 4-91 in the 14th over - not yet a crisis, but the Hurricanes would have felt they had the momentum.
Instead, Gibson belted 39 from 27 deliveries, with five fours and a six, as they put on a quickfire 44 for the fifth wicket.
Carey took 2-29 from her four overs.
After Hobart slumped to 6-59, captain Elyse Villani and Hayley Silver-Holmes gave them a glimmer of hope with their 40-run stand for the seventh wicket.
Then Day bowled Silver-Holmes for 18 from 14 deliveries and Sutherland bowled Villani for 38 off 21 balls to kill off the late rally.
Kapp took 2-29 from her four overs, while Sutherland also snared two and Day cleaned up the tail on the way to 4-17 from three overs.
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