Mexico third baseman Luis Cruz, peeved, motioned to pitcher Arnold Leon to put the next one in batter Rene Tosoni's ribs.
Leon missed twice, drawing a warning to both dugouts. He then plunked Tosoni square in the back on the third try, and the melee was on like Donkey Kong.
This was not your usual swing-your-partner baseball bench-clearer - there were real haymakers thrown and the police had to come onto the field.
Several Phillies featured in the fisticuffs, most prominently Canada outfielder Tyson Gillies, who tossed Mexico reliever Alfredo Aceves in a Haystacks Calhoun move, then dived back into the scrum for more.
Another Fightin' Phil involved in the tussle was Mexico catcher Sebastian Valle (whose major-league teammate, Canada pitcher Phillippe Aumont, sent out this tweet to Phillies fans: "How about Sebastian Valle swinging at people with his catchers mask. #stupid").
And among the seven players ejected was Canada's Pete Orr, a familiar face at Citizens Bank Park and in Lehigh Valley IronPigs garb.
Once order on the field was restored, Mexico fans threw debris at the Canada dugout, hitting pitching coach Denis Boucher. A Canada player tried to go into the stands, but was stopped.
After play restarted, a ball was thrown from the stands, missing Canada first base coach, Larry Walker.
Mexico finished at 1-2.
Canada is 1-1 going into its game Sunday against the United States.
In the quieter WBC games, host Puerto Rico eliminated Venezuela, 6-2, and Carlos Santana homered as the Dominican Republic beat Spain, 6-3, in San Juan. Yasmany Tomas hit a three-run homer to help Cuba rout Chinese Taipei, 14-0, in Tokyo.
Rivera retires officially. The Yankees' Mariano Rivera, the indisputable greatest closer of all time (608 saves don't lie), officially announced that he will retire at the end of the season.
He then went out and pitched a 1-2-3 fifth inning against Atlanta in a 2-1 loss to the Braves.
The Yanks won't be playing the Phils this season, but it's worth a trip to the Bronx or Baltimore to give the 43-year-old legend a cheer in his farewell season.
For real. Among Arizona pitchers scheduled to throw in the Diamondbacks' "B" game on Sunday against San Francisco is Josh Booty.
The 37-year-old ex-LSU QB and ex-Marlins infielder won his invite on a reality-TV show, The Next Knuckler, in which knuckleball wizard Tim Wakefield taught contestants the pitch.
(Booty does have an 89-m.p.h. fastball, so he may have a chance to be baseball's Kelly Clarkson.)
Contact Michael Harrington at firstname.lastname@example.org
This article contains information from the AP.