At Jesse Bynum Field, Pontotoc took advantage of 13 walks, five of them in a four-run fourth.
"The key is being disciplined at the plate and just getting baserunners on," said Pontotoc assistant coach Tommy King. "They capitalized tonight."
The Red Sox sent 14 to the plate and added nine runs in the fifth, three on consecutive RBI singles from Corey Smith, Blake Littlejohn and Dylan Earnest before Clark's grand slam.
Tyler Beaty walked 10 but worked himself out of most of the trouble for Pontotoc. He gave up only three hits, two of them home runs to Ethan Estes and Lew Johnson. Johnson's three-run shot in the bottom of the fourth made it 9-4 before Pontotoc (21-3) answered in the fifth.
"We've been scoring a lot of runs but we've had some good pitching too," said King, filling in for coach Nickey Browning, out with kidney stone surgery. "The ump was tight on both sides and I thought Beaty did a nice job putting it in there. When he's on, he's tough."
Beaty got out of a bases loaded jam in the third, walking the bases loaded before Dylan Earnest made a catch in foul ground against the first base side wall to end the inning.
Pontotoc got a solo shot from Devin Rogers in the second inning for a 2-0 lead and scored five straight on wild pitches before Littlejohn's two-run shot off Will Cockrell for a 9-1 lead.
"We're somewhat of a power-hitting team but it's usually been a pretty good mix," said Pontotoc assistant Jason Earnest. "The top of our order hit the ball pretty hard."
Estes had two of the Stars' three hits and three RBI, two on a fifth-inning bases-loaded single. Beaty hit three batters to load them up.
The tournament begins a four-game schedule today at 10 a.m.