HUGHES SPRINGS, Texas—Pitching depth can be a luxury in high school baseball. It doesn’t hurt to be a little lucky, too.

Hughes Springs (26-5) discovered both Saturday on its home turf as Harleton rallied to beat Class 2A’s ninth-ranked Mustangs, 11-3 and 8-7, earning a berth in the Region III-2A semifinals next week against Hemphill.

The Mustangs led 7-5 going to the bottom of the seventh of Saturday’s decisive third game, but Harleton (25-6) pulled within a run when Connor Lloyd walked with the bases loaded. Billy King’s hard grounder rolled into center for a hit afte...