Juan Manuel Marquez takes fifth on Manny Pacquiao rematch

Boxing is back at the Forum, and Juan Manuel Marquez — 13-0 in that historic venue — is back in a familiar spot.

Ready to fight Manny Pacquiao for a fifth time… maybe.

Marquez beat Mike Alvarado by unanimous decision Saturday night in a thrilling 12-round welterweight title eliminator that set the stage for yet another showdown with Filipino superstar Pacquiao.

But Marquez (56-7-1, 40 knockouts) wasn’t ready to commit to a fall rematch with Pacquiao, a fighter he knocked out in the sixth round in December 2012.

“I’ll relax, I don’t know at the moment,” said Marquez, 40, who is 1-2-1 against Pacquiao. “But any decision that I make will be good for me, my family, and all of the Mexican fans.”

Having won world titles in four weight classes, from featherweight to junior-welterweight, Marquez is looking to become the first Mexican fighter to claim titles in five divisions.

The fight against Alvarado (34-3, 23 KOs) got better with each round.

Marquez controlled the first three rounds, as the normally aggressive Alvarado seemed reluctant to throw punches, tentative and tactical, keeping his hands high and protectively bracketing his face. Occasionally, Alvarado unleashed big swings, but most of those missed their target.

The crowd of 12,090 roared its approval in the fourth and fifth as the power-punching Marquez landed a series of combinations.

Alvarado thumped his chest at the end of the sixth round, as he did a better job of stalking Marquez around the ring — but he paid the price too, walking into the piston-like punches of Marquez.

After Marquez landed more than half his punches in the seventh round, Alvarado’s trainer implored him to “let your hands go” and “beat this old man up.”

Marquez didn’t look old in the eighth, when he landed a right hand at the end of the round that knocked down Alvarado.

Alvarado climbed to his feet but had to be pointed to the correct corner at the end of the round. However, that seemed to wake him up, and he returned the favor in the ninth, knocking down Marquez with a right of his own. Suddenly, the fight was a two-way slugfest that paid homage to the rollicking history of the Forum.

In the 11th round, Alvarado landed a flurry that stunned and staggered Marquez, but Marquez never touched the canvas and therefore avoided the knockdown.

Once a home of world-class boxing, the Forum had not staged a fight since 2001, two years after the Lakers and Kings relocated to Staples Center. In part to reestablish the Forum as a boxing mecca, The Madison Square Garden Co. invested $35 million to refurbish the venue, a place where Muhammad Ali fought Ken Norton in 1973, where Oscar De La Hoya made his pro debut in 1992, and where Marquez rose to stardom as one of the best fighters of his era.

It was the Forum debut for Alvarado, 33, as he didn’t begin his pro career until three years after it was mothballed as a boxing venue.

Heading into the fight, Marquez and Alvarado were coming off defeats.

Marquez followed his 2012 knockout of Pacquiao with a split-decision defeat to Timothy Bradley last October.

Alvarado lost in his hometown of Denver last October when he was knocked down twice in the eighth round by Russia’s Ruslan Provodnikov, then didn’t come out of his corner after the 10th round, relinquishing his junior-welterweight world title.