The Hawks lead the 51-team field with 40 points, followed by Owen J. Roberts with 35.5.
South brought 11 wrestlers, with six of them now in the consolation round.
Mendez (40-7) won his quarterfinal, 5-1, over Penncrest's Dayton DelViscio, who entered the bout 36-1.
"I don't look at kids' records. It might throw you off guard," Mendez said.
Mendez will be back on the mat Saturday at 11:30 a.m. to face Downingtown West's Doug Zapf, who is considered the favorite in the weight class.
Mendez and Zapf have trained together at a club in the offseason and squared off last summer at the state freestyle meet.
"I'll be going against one of my good friends, Doug Zapf," Mendez said. "It should be a pretty decent match, neck and neck."
Trampe continued to pile up the points, earning a 25-15 major decision over Unionville's Jake Taylor. He is a heavy favorite to win the 132-pound crown.
Cary Palmer decisioned Garnet Valley's Nick Puliti, 8-3, setting up what should be a very competitive semifinal against Conestoga's Eric Hutchinson.
Riley Palmer, his twin, was wrestling at the same time on an adjacent mat. He decisioned Penncrest's Ryan Stocku, 4-1, and should have a pretty tough test against Dan Mancini of Owen J. Roberts.
Doyle continues to demolish people. He built an 11-3 lead before pinning Spring-Ford's Tyler LaRocca in 1:21. He's all but certain to face Upper Darby's Brian Kennerly in the final in a matchup of PA Power Wrestling's top two 220-pounders in the state.
Council Rock North is in sixth place, led by semifinalists Luke Lucerne (106) and Aidan Burke (120). Five other Indians are in the consolations.
Lucerne, a freshman, picked up an 11-2 major decision over West Chester East's Corey Celenza.
"I definitely thought I would win. I gave my absolute effort, and points take care of themselves," he said.
Lucerne's semifinal opponent is Quakertown's Josh Stahl.
"It's exciting. I'm looking forward to it. I'm focused on staying in the present," he said, adding that he's not looking past Stahl. If Lucerne defeats Stahl, he'll face the Mendez/Zapf winner.
Burke won his quarterfinal bout, 7-3, over Boyertown's David Campbell. He'll meet West Chester Henderson's Jacob Reid in the semifinals.
William Tennent is in 14th place. Freshman A.J. Tamburrino won his first bout by technical fall, then lost a heartbreaking 4-2 overtime decision to Norristown's Eric Fuentes.
Tennent's David McCoy was trailing, 5-4, late in his bout against Spring-Ford's Jack Files before taking him down and pinning him.
"I needed a takedown. He was a really strong kid. I took him down and put him on his back. I wanted it," he said.
McCoy opened with a first-period pin in the preliminaries.
"I love having two matches. It's a good warmup. I push it," he said.
McCoy's two wins send him to the semis against Oxford's David Cox.
"It puts me in a good position," he said. "It's a big match for me (Saturday). I'm excited. I want it."
Neshaminy is in a four-way tie for 25th place. Jackson Erb lost in the ultimate tiebreaker at 126 to drop into a consolation bout against an old rival, Pennsbury's Antonio Martoccio.
Neshaminy's Kyle Osterhoudt was holding on to a 2-1 lead late in the third period at 285 when Ridley's John Sheldon went for a takedown. But it was Osterhoudt who got the takedown and pin at 5:32.
"I turned my hips so he would fall. I got my two and pinned him. That was icing on the cake," he said.
Osterhoudt will challenge Avon Grove's Josh Walls in the semifinals. Back on Jan. 14, the two met up at the Souderton Big Red Duals, with Walls winning, 2-0.
"I've gotten a lot better. We'll see (Saturday) morning," Osterhoudt said. said. "If I win the next one, I'm going to states. That's the goal."
Harry S. Truman brought four wrestlers to regionals, and Gunnar Fuss is in the semifinals. He used a takedown in overtime to beat Garnet Valley's Matt Marino, 3-1. He'll next face Bayard Rustin's Brett Kaliner.
Pennsbury has two wrestlers in the consolations. Bensalem has one.