Alex Caldera was thrown out at second base to end the fourth.
The Vikings got one back in the fifth when Adan Mejia scored on a Billy Huyler single, but the Eagle defense nabbed the third out with two men on.
In the seventh, Edward Castro entered to relieve starter Isaac Mejia; a move that proved quite costly to the Viking cause.
Southwest, which began the inning with a 9-3 advantage, saw Tyler Martin and Ernie Silva walk and Armendariz reach first on a hit-by-pitch to load the bases.
Lopez smacked a double that scored Martin and Silva and Armendarez scored on Ainza's sacrifice fly.
Lopez then scored on a passed ball to give Southwest its 13th run.
The Vikings made a final rally in the bottom of the seventh as they managed to toy with Ainza, who relieved Martinez.
Castro hit a single, stole second, and scored on an Isaac Mejia double.
Huyler, Isaac Mejia, Jarret Hilfiker and Josh Angulo all scored and two batters were hit with pitches, but Adan Mejia flied out with two men on to seal the victory for the Eagles.
"We played well offensively," said Southwest coach Mickey Carter. "I really think Bryan (Martinez) pitched a good ball game.
"(Martinez) did a good job of making the pitches he needed to when he needed to," Carter said.
Carter said the final Holtville rally was beginning to get to his team, but he conceded the four runs it scored in the top of the inning provided a good cushion for Southwest to rest on.
"You've got to give Holtville a lot of credit," Carter said. "I'm glad we were in good enough shape to win."
The Eagles improved their record to 10-13 (3-6 Imperial Valley League) with the win and Carter is not ruling out a trip to CIF playoffs.
"I don't have a problem with trying to get into the playoffs," Carter said. He added the Eagles would be in decent shape for a berth if they win their final three games.
Martinez agreed that Southwest is not looking for its season to end anytime soon.
"We just need to play like this every game," Martinez said. "All we have to do is focus."
Holtville (2-7 IVL) hosts Calexico at 4:15 p.m. Tuesday and Southwest hosts Palo Verde at 4:15 p.m. Friday.
Palo Verde 5, Central 1
The Imperial Valley League leading Central Union High baseball team stumbled against Palo Verde in El Centro on Friday, losing 5-1.
Mario Gastelum took the loss for the Spartans as they fell to 6-2 in league.
Gastelum and Raul Cazares each finished 2-for-3 for Central, which committed four errors.
The Spartans host Imperial at 4:15 p.m. Tuesday.
Imperial 7, Calexico 2
IMPERIAL — Eddie Martinez improved his season record to 6-1 as he pitched a complete game to lead the Imperial High School baseball team to a 7-2 Imperial Valley League victory over Calexico here Friday.
Martinez finished with five strikeouts and gave up two earned runs.
Tied 2-2 going into the sixth inning, the Tigers scored five runs in the frame to break the game open.
Leading the Imperial offense were Chris Cabrera with two hits, a double and a run and Eric Ramirez, who finished 1-for-2 with a run.
Damien Lopez led Calexico with a home run.
Mountain Empire 11, Calipatria 1
CALIPATRIA — The Calipatria High baseball team was no match for Mountain Empire here Friday losing 11-1 in Citrus League action.
Calipatria did itself no favors committing eight errors in the game.
The Hornets (9-3) play at Warner High School in Warner Springs at 3:15 p.m. Wednesday.