Teams from Texas, Indiana and Panama also won in the double-elimination tournament, which played its first four contests on Thursday.
Canada, set to face Panama on Sunday, led 7-1 after the first inning, only to see Mexico storm back for an 8-8 tie after two frames. A run-scoring double play, followed by a wild pitch, put Canada back in front in the third.
It stayed there for good with help from some fine defensive plays, most notably center fielder Thomas Neal's full-extension diving grab with a runner aboard in the bottom of the third. On offense, Canada mustered 13 singles and 10 walks, as Steven Moretto led the way by going 3-for-3 and reaching base in all five of his plate appearances.
Ramon Ballina smacked two of Mexico's four home runs and drove in three. His team will clash with Uganda in an elimination contest on Saturday.
Uganda, the first African team in the tournament's 66 years, fell, 9-3, to the Latin American squad from Panama in Friday's other international contest. James Gonzalez collected a game-high three hits for Panama, which broke things open with a five-run second inning.
Panama's pitchers also piled up 16 strikeouts, including seven in 2 2/3 innings from starter Julio Goff. Uganda managed three hits, one a two-run homer by Daniel Alio.
In the day's first matchup of United States teams, San Antonio, Texas, grabbed an early 4-0 lead and held on for a 5-2 victory over Parsippany, N.J. Texas leadoff hitter Jordan Cardenas homered to start the bottom of the first and later threw 2 1/3 scoreless relief innings.
The Southwest regional champions also benefited from the Mid-Atlantic squad's three errors, which led to three unearned runs in the second against starter Emil Matti.
New Castle, Ind., representing the Great Lakes, finished off the day's action with a late burst of offense to beat the Northwest's Gresham, Ore., team. The game was scoreless until the bottom of the fifth, when Indiana plated four runs to set up a 4-0 win. Bryce Pinkard crossed home on a wild pitch for the first tally, and Mason Gillis added a two-run double down the right-field line.
Cayden Smekens, Niah Williamson and Pinkard combined on a shutout for Indiana, which will battle Texas on Sunday.
Oregon will tangle with New Jersey on Saturday for the right to remain in Williamsport. In other elimination games, Curacao will meet Germany, and Connecticut will face Nebraska.
Andrew Simon is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.