Defending champion Dominican Republic exploded for four runs in the second inning as they routed Canada 9-2 in their World Baseball Classic opener.
Welington Castillo hit a two-run homer in a four-run second inning and Jose Bautista blasted a three-run home run in the sixth in front of a crowd of 27,000 at Marlins Park.
In the night match, Italy belted four home runs early and rallied behind a five-run ninth inning to upset Mexico 10-9.
Right handed pitcher Carlos Martinez tossed a solid game in his tournament debut as the 25-year-old pitched four innings, allowing just three hits and one run for the Dominicans. He also had three strikeouts and one walk.
The bullpen did the rest as Fernando Rodney and Jeurys Familia combined to strike out all three Canadian batters they faced in the ninth.
Canada falls to 3-6 all time in the tournament as they are trying to advance beyond pool play to the second round for the first time.
Both Pool C teams resume play at Marlins Park on Saturday, when Canada takes on Colombia and the Dominican Republic faces the Americans.
Following their highly anticipated game against the USA, the Dominicans conclude play against Colombia on Sunday.
Former Major League Baseball all-star Ryan Dempster took the loss for Canada. The 40-year-old Dempster gave up four runs in the second inning in his first competitive game since the 2013 World Series.
Dempster is one of 63 former MLB players in the international tournament. There are just 25 MLB players from last season taking part as many owners expressed concerns that their players might get injured.
Baseball's birthplace, the United States, has never won the WBC. The US pitchers are Tampa Bay's Chris Archer, Washington's Tanner Roark, Toronto's Marcus Stroman and Kansas City's Danny Duffy, but few relievers have recent MLB experience.
Mexico had a comfortable four-run lead heading into the bottom of the ninth before their collapse in Guadalajara.
Italy's John Andreoli hit a walk-off single to cap the final inning comeback. Francisco Cervelli, Chris Colabello and Alex Liddi hit consecutive doubles to get the rally started.
Two of four teams advance from first-round pools in Seoul, Tokyo, Miami and Guadalajara, into second-round play at Tokyo and San Diego that will determine the four semi-finalists who play March 20-21 in Los Angeles.
The 16-team competition concludes with the final at Dodger Stadium on March 22.