Mexico (1-1) next plays Canada (2-0) on Thursday night at 8 p.m. ET at Chase Field in the final Pool B game for both teams.
Mexico now controls its destiny in the tournament.
South Africa fell to 0-2 in Pool B, eliminating that country from the next round of the tournament.
"We're the only team with two losses and still have to play the USA," South Africa manager Rick Magnante said. "It's a big game for us and we know it's going to be a big game for them because it's a must-win for them."
|POOL B SCENARIOS|
If it defeats Canada on Thursday.
If it loses to Canada, and USA loses to South Africa by seven or more runs.
|Team USA advances:|
If Canada defeats Mexico on Thursday, and USA defeats South Africa on Friday.
If Mexico defeats Canada and scores three or more runs, and USA defeats South Africa on Friday.
If it wins Thursday in its game against Mexico, finishing Pool play with a perfect 3-0 record.
If it loses Thursday against Mexico, but allows two runs or less.
Mexico knows the feeling well, having gone into Wednesday night's game knowing that they should beat South Africa and if that didn't happen, it was back to Mexico with tails between legs.
"It was an almost-expected victory over South Africa," Mexico manager Paquin Estrada said. "But it doesn't mean we don't have to make an effort [Thursday] night, right?"
That is correct, and there is some question as to the availability of center fielder Karim Garcia. He started Thursday night's game with a triple and scored Mexico's first run of the Classic. But he suffered a pulled hamstring while advancing to third base in the fifth inning and had to leave the game.
"He pulled his hamstring a little bit, but he wants to play [Thursday night], and we will keep an icepack on him all night and make sure he can play [Thursday] night even though he is not 100 percent."
Garcia has 10 years worth of Major League experience.
Right-hander Francisco Campos' career has been spent in the Mexican League and he held South Africa scoreless through four innings. And by then, he had a five-run lead.
Mexico's scoreless streak in the Classic ended at nine innings, thanks to Garcia's triple and a sacrifice fly to right field by Jorge Cantu. Mexico tacked on another run when Vinny Castilla's doubled to left-center field, moved to third on an infield and scored on the ninth wild pitch in the tournament by South Africa pitchers.
South Africa, which demonstrated plenty of comeback ability in Tuesday night's loss to Team Canada, showed the same kind of spunk in the fourth when they scored three runs. Center fielder Jason Cook drove in two runs with a triple and scored on Kyle Botha's infield single.
Mexico, though, regained control of the game with a three-run rally in the fifth.
The offense, which struggled so badly against Team USA, unleashed a 12-hit attack against South Africa with Cantu and Castilla leading the way with three hits apiece. South Africa pitchers issued nine walks, giving them 20 free passes in two games.