A player-of-the-match performance from Riverside captain Sophie Parkin led the Blues to a 60-run win over Mowbray on Friday night.
After top-scoring with 45 last weekend to help her team reach 127, Parkin ripped through the Mowbray middle-order, claiming four bowleds and one LBW in a brutal spell of 5-11 off eight overs.
The haul came after Mowbray made a confident start to the chase, reaching 31 without loss before captain Lynn Hendley was bowled for 19.
Number four bat Georgie Nicolson (13) was the only other Eagle to reach double figures as wickets began to tumble regularly at both ends.
Maddison Hill gave Parkin plenty of support and also kept things tight, snaring 2-7 off six overs.
The next round will see Mowbray play South Launceston, who polished off the Lions inside one session last weekend, while Riverside will host Launceston at Windsor Park.