Junior forward Treg Setty scored 16 points and No. 18 Mason County got away from Bishop Brossart in the fourth quarter to move on to the 10th Region semifinals.
The Royals managed a 51-46 victory at the Mason County Fieldhouse on Friday night despite an early deficit and a tie game heading into the final period.
Mason County will take an eight-game winning streak into Saturday's matchup with Pendleton County.
No. 5 Clark County will play Scott in the other semifinals. The two winners will meet in Monday night's championship game with a trip to Rupp Arena on the line.
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Ashland Blazer 75, Fleming County 54 (16th Region): Dylan Delaney made five three-pointers and finished with 24 points to lead the Tomcats into the semifinals with a victory at Morehead.
Ashland Blazer led by only two points heading into the fourth quarter, where they outscored Fleming County 30-11.
Both teams committed 24 turnovers and neither was very successful from the free-throw line. The Tomcats were 12-for-21 from the line and Fleming County was 2-for-7.
Ashland Blazer will play in the region semifinals on Saturday against East Carter, which defeated Lewis County 50-41 earlier Friday night.
Elizabethtown 52, Nelson County 51 (5th Region): Junior guard Natalie Greenwell scored 15 points an the Panthers didn't get their first lead of the game until just 7.7 seconds remained in the fourth quarter.
E-Town advanced to Saturday's region championship game at Hart County against Marion County in a highly anticipated game that will produce one of the favorites to win the state tournament.
Marion County, which defeated Green County 76-60 in Friday's other semifinal, is the second-ranked team in the state and features freshman phenoms Makayla Epps and Kyvin Goodin-Rogers.
E-Town is ranked No. 8 in the state.
Harlan County 44, North Laurel 41 (13th Region): Heather Maggard scored 22 points and Whitney Gilliam dished out six assists in Harlan County's upset victory over North Laurel in the region semifinals at Corbin.
The Black Bears will play Clay County for the region title Saturday.
Ryle 40, St. Henry 36 (9th Region): Jenna Crittendon and Abby Jump scored 13 points each to help the Lady Raiders win their region semifinal game at Northern Kentucky University. Ryle will play Boone County for the region title Sunday.