"Honestly, I better do something or I'm never going to be able to live in Columbia again," Matthews said of what he was thinking at the plate. "He threw me a good slider there at the end that I held off of and fortunately I walked."
South Carolina relievers Tyler Webb and Matt Price combined to throw seven scoreless innings to lead the Gamecocks (49-18) to the finals, where they'll face Arizona (46-17) at 8:10 p.m. ET on Sunday in the first game of the best-of-three series.
South Carolina, the two-time defending NCAA champions, is trying to join USC (1970-74) as the only program to win three straight championships.
Webb and Price (seventh round, Orioles) entered after Arkansas scored two early runs off starter Colby Holmes and was threatening again in the third. Webb got out of the jam and held the Razorbacks to two hits in four innings before Price finished the game with three innings of one-hit ball.
"Tyler Webb had a real sneaky fastball and he can move it around the plate," Arkansas third baseman Matt Reynolds said. "He didn't really have his offspeed working tonight, but we had that thought in the back of our head.
"Price just did what he always does, just found the zone and throws a good slider."
Reynolds (second round, Mets) drove in both Razorback runs, the second coming on a sacrifice fly against Webb. Reynolds hit a fly ball down the right-field line with runners on second and third with one out that was caught on a sliding play by Matthews. Catcher Jake Wise scored, but Matthews' catch saved another run from scoring.
"Once we got out of that, with the great catch by Adam and everything, just tried to pound the strike zone and get it to Matt," Webb said.
Arkansas right-hander D.J. Baxendale (10th round, Twins) pitched with relative ease until losing control in the fifth.
South Carolina left fielder Tanner English singled, stole second and scored on Pankake's single to center, which was preceded by a walk to second baseman Chase Vergason.
Baxendale, who issued a career-high five free passes, walked his final two batters -- center fielder Evan Marzilli (eighth round, D-backs) and first baseman Christian Walker (fourth round, Orioles) -- the second of which brought across the tying run.
Arkansas turned to its bullpen, as left-hander Trent Daniel got a one-pitch out before righty Colby Suggs struck out Matthews to end the inning.
"Colby, he's a bulldog," Arkansas head coach Dave Van Horn said. "When we bring him in it's usually a tight situation. We wouldn't be here if it wasn't for him."
Astin replaced Suggs with two on in the seventh. L.B. Dantzler hit a hard comebacker to the mound that went off Astin's glove for an infield single to load the bases before Matthews drew the game-winning walk.
"Certainly pretty close," Matthews said of the pitch. "I just wanted to get my foot down that last pitch and see if I could see and I saw it away and I about swung at it like I did earlier in the game, and thankfully I held up."