Dan Triglia graduated from Manteca High but now coaches East Union’s baseball team across town.

One player of note that went through East Union’s program during his tenure is Gene Ballardo, whom he coached as a freshman.

And guess who the head skip is at Manteca?

“It’s kind of interesting how that all worked out,” Triglia said.

It’s just one of many interesting tidbits that have fanned a fiery three-way, intra-city baseball rivalry that includes Sierra.

At Tony Zupo Field in Lodi today, teacher meets former pupil for a third time this year as Valley Oak League co-champion East Union (16-6) encounters VOL No. 3 seed Manteca (18-8) in the second round of the Sac-Joaquin Section Division-IV playoffs. The first pitch is scheduled to be thrown at 9 a.m.

“It’ll be the first time for us to start this early in the day, but I don’t think it will be an issue,” Triglia said. “These are two good teams in a playoff situation, so it doesn’t matter what time of day or night the game starts. We’re going to come out focused.”

The best-of-three series resumes Monday, including the “if necessary” rubber match. The victor will face Oakdale or Western Athletic Conference runner-up Los Banos in the title round on Monday, May 30.

If their regular-season series is any indication, an all-out dogfight is imminent.

Manteca rode ace pitcher Kevin Peck to a 1-0 victory on April 27, but two days later East Union held off a late Buffalo charge to prevail 8-7 and even the score.

East Union has won 11 of its last 12, while Manteca is a winner of six of its previous seven. Their last losses were to each other.

“We’re both coming in with some momentum,” Ballardo said. “It’s going to be a good game for the players to experience and for the fans to watch.”

For Manteca, today’s game will be its third in the postseason. The Buffaloes were paired with River City in the out-bracket game, winning 5-0 behind a two-hit gem from Peck and a three-run homer from Danny Gouveia Monday. On Thursday they upset top-seeded Central Catholic, 13-8.

“The guys were very focused in practice (Friday),” Ballardo said. “There was no talk about who they just beat — Central Catholic has been put in the past. They’re looking forward to see what they can do against a good East Union team.”

The Lancers, meanwhile, opened with a commanding 5-0 win over Galt and were led by sophomore pitcher Jordan Kron’s 11-strikeout masterpiece.

“I believe we’re peaking at the right time and playing our best baseball in all three phases of the game,” Triglia said.

While there are no secrets or surprises up anyone’s sleeves, neither of today’s starting pitchers — Cory VanWarmerdam (3-1, 2.59 earned run average) for Manteca and Zac Carrillo (4-0, 2.47) for East Union — saw time on the mound when the two clubs met in the regular season.

Manteca boasts a tidy 1.57 team ERA and a .324 batting average vs. East Union’s 1.78 and .324.

“We’re so similar in a variety of different ways,” Triglia said. “We’re almost mirror images of each other — it’s kind of scary.”

The Buffaloes do have one advantage going for them — playoff experience. Nearly half of the players on the 2010 playoff roster are back this year playing key roles.

East Union’s last postseason appearance was in 2008, when it made a surprising run to the section championship finals only to lose to VOL foe Oakdale.

“In my opinion (playoff experience) is very valuable,” Ballardo said. “We have 12 guys who have been there and already know what to expect. They know what we have to do win the ballgame and the series. We like our chances.”