The weightiest questions the LA Galaxy faces as it begins defense of the MLS Cup title captured just two and a half months ago begin and end with Riqui Puig.

Essentially: How do you play without Riqui Puig?

The speedy Spanish playmaker — effortlessly and gorgeously slicing and dicing through opposing midfields — is the heart of the electric attack that fueled the club’s record sixth league championship and first in a decade. He’s out until at least mid- to late summer, and he’s a rare commodity: irreplaceable. For real.

The Galaxy in Sunday afternoon’s opener welcome for-now-merely geographical rival San Diego FC to MLS, and things are going to look a lot different.

Puig, who tore an anterior cruciate ligament — then, in a heroic performance, played on and concocted the late winner — in the Western Conference title game against Seattle, isn’t the only difference-maker that’s missing. Major League Soccer’s economic hammer came down hard on LA, as it does with most of its champions.

Dejan Joveljic, with so many important strikes among his 21 MLS goals last year, left three weeks ago for Sporting Kansas City in the league’s first straight-cash deal, worth $4 million. That leaves quite the void up top. Mark Delgado, Puig’s primary foil in midfield — so key to connecting LA’s attack — headed up the Harbor Freeway to archrival Los Angeles FC last month.

That left dynamic wingers Gabriel Pec and Joseph Paintsil from the front five in last year’s most typical starting XI, and Paintsil, dealing with a quad injury, won’t be on the field until — probably, hopefully — sometime next month.

They can’t be who they were. They won’t be who they were. It’s no longer Riqui’s team. And that’s OK. It’s now about “collective efficiency.”

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