• Box score: Cuba 3, Puerto Rico 2
The Cuban team improves to 1-2 with the victory, while Puerto Rico is now 0-3 in pool play.
"This was a very important game, and both teams deserved to win, but only one can," Cuba manager Alfonso Urquiola said. "It was an intense game. We both knew what another loss meant."
Catcher Frank Morejon led off the eventful 10th inning with a sharp ground ball to third base that Yadier Rivera fielded and airmailed over the head of first baseman Neftali Soto. Center fielder Roel Santos followed with a game-winning single to drive home pinch-runner Yosvani Alarcon from second base.
"I'm very proud of my team and the way they fought," Puerto Rico manager Eduardo Perez said. "We put ourselves in a position to win the game. Now, we are going to need some help from the other teams to advance."
• Caribbean Series coverage
Puerto Rico had its chances. Santurce loaded the bases in the ninth inning, but Cuba's Andres Santiago struck out Rivera swinging to end the inning and squash the scoring threat. Cuba left two runners on base in the bottom of the ninth to send the game into extra innings.
The teams traded runs in the first inning, and Cuba pulled ahead, 2-1, in the second when left fielder Yadiel Hernandez scored on a single by first baseman William Saavedra.
Puerto Rico tied the game, 2-2, in the top of the fifth when right fielder Jorge Padilla scored on a single by Soto.
Jesse Sanchez is a national reporter for MLB.com. Follow him on Twitter @JesseSanchezMLB. This story was not subject to the approval of Major League Baseball or its clubs.