JACKSON TWP — Hempfield may have had ideas of a huge upset in the first round of the WPIAL Quad A football playoffs. What the Spartans got instead was a demolition job courtesy of host Seneca Valley. The Raiders’ defense allowed Hempfield just 21 yards of offense in the first half, forcing the Spartans into four 3-and-outs in that span, paving the way to a 50-20 victory Friday at NexTier Stadium. SV (9-1) will face Mt. Lebanon, a 31-7 winner over Butler, in the quarterfinals next Friday at a site and time to be determined. “The goal is to advance and we’re happy to be moving on,” said Raiders’ coach Don Holl. Seneca’s offense was clicking right from the start, beginning the game with a 9-play, 65-yard drive capped with Forrest Barnes’ 1-yard touchdown run. It was the first of four scores in the game for Barnes, who ran for 104 yards and added 95 receiving. Hempfield, which scored all of its points and gained most of its yards in the second half after the Raiders’ reserves had taken the field, had an opportunity to make things interesting midway through the first period. With the Raiders leading 6-0, Hempfield defensive back DeLorian Day intercepted Jordan Brown’s pass and set his team up at the Raiders’ 37.