The First Division outfit started as slight favourites against runaway Second Division leaders Dumfries at People's Park. And it was Stander who was the difference between the sides as the Aberdeen outfit carved out a comfortable win by five wickets.
Stander, who has not played for Scotland since the T20 World Cup qualifiers last February, first claimed four cheap wickets as Dumfries were restricted to 179. National Academy youngster Tom McBride top-scored for the visitors with 47 while Josh Geary made 46.
Another highly rated youngster, Michael Leask, led Stoneywood's chase with 45 before Stander completed his personal contribution with a hard-hitting 41 to see the home side claim their place in the last four.
Elsewhere Stirling made it a double of wins for First Division sides with a shock win over McCrea FS West.
A rain-affected match at Hamilton Crescent saw Stirling skipper Phil Rees top-score with an unbeaten 49 in his side's 190. West, set a revised target of 217 in 41 overs, lost wickets at regular intervals and, despite a battling 46 from skipper Ian Young, they fell 42 runs short.
However, Uddingston flew the flag for the Premier Division to deny Heriot's a hat-trick of wins for lower league teams. The top flight outfit looked up against it when they slumped to 170-8 chasing Heriot's 208 at Bothwell.
Niall MacLeod, Josh Johnson and Ricky Bawa held their nerve as Uddingston won with four balls to spare with their last pair at the crease.
The weather was the winner at Titwood where Dunfermline Knights had reached 175-3 from 41 overs in their clash with Clydesdale before heavy rain set in.
They will replay next Sunday, with the winner sure to be installed as joint favourites with Uddingston to go on and lift the trophy.