Mexicali 4, Culiacan 2
Starter Edgar Osuna and the Mexicali bullpen held Culiacan to six hits, allowing four early runs to hold up en route to a series-opening win. Culiacan's two runs came in the sixth, when Luis Alfonso Cruz, who accounted for half of Culiacan's hits, ripped a two-run homer off reliever Francisco Gil. But that was all Mexicali would allow.
Outfielder Ben Guez, a Tigers Minor Leaguer, led the way offensively for Mexicali with two hits, including a solo homer in the third. The club capitalized on Culiacan's mistakes and manufactured the rest of its runs. Gil Velazquez got Mexicali on the board in the second inning on a sacrifice fly. Oscar Robles scored in the fifth on Sergio Gastelum's fielding error and Guez came home later that inning on a wild pitch. Box score
Navojoa 4, Los Mochis 3 (10 innings)
Navojoa needed two walks, a wild pitch and a throwing error in the 10th inning to pull out the victory and take an early series lead against Los Mochis. With two outs the game tied, 3-3, in the bottom of the 10th, left fielder Jon Weber tallied his fourth hit of the night, a single to center. Weber moved to second on a wild pitch, waited out an intentional walk, then advanced to third on another walk. Finally, third baseman Rodolfo Amador's throwing error allowed Weber to score the walk-off run.
Navojoa starter Jose Oyervidez struck out six and allowed only one run on six hits in six innings, while right-hander Jose Manuel Lopez picked up the win with two strong innings in relief. Box score
Hermosillo 7, Guasave 3
Down by one entering the bottom of the eighth, Hermosillo pounded Guasave's bullpen for five runs to take the first game of this playoff series. Jose Aguilar led off the eighth with a single, moved to second on a sacrifice bunt and scored on Carlos Alberto Gastelum's single to center.
With two outs and the bases loaded, Yunesky Sanchez singled home Gastelum and Heber Gomez, and Jesus Loya followed with a two-run single to cap off the rally. Sanchez led the way offensively for Hermosillo, finishing 2-for-4 with a homer, three RBIs and two runs. Japhet Amador drove in two of Guasave's runs with a fourth-inning double. Box score
Adam Berry is a reporter for MLB.com. Follow him on Twitter at @adamdberry. This story was not subject to the approval of Major League Baseball or its clubs.