SAN FRANCISCO — Hall of Famer Juan Marichal mingled in the San Francisco clubhouse and waited patiently for his chance to share a kind, congratulatory word with Madison Bumgarner.

Marichal understood it would be tough to find a moment with the man of the night. MadBum, the man of the postseason, more like it.

One of the greatest pitchers ever thinks the world of one of baseball’s brightest young arms, so standing in line to speak to the lefty was no big deal.

What Bumgarner did to pitch the Giants within one victory of another World Series championship certainly was.

The Southern southpaw tossed a four-hit gem in his latest brilliant postseason start, and the Giants beat the Kansas City Royals 5-0 on Sunday night to reach the cusp of a third championship in five years.

“It’s what you set your sights for before you go out there, you want to finish the game,” Bumgarner said.

The best-of-seven series shifts back to Kansas City and Kauffman Stadium for Game 6 on Tuesday night, and the Royals will try to stave off elimination with the blue-clad crowd behind them.

If the Royals can push it to a Game 7, they might just see Bumgarner come out of the bullpen.

“He’s so smooth. I say that he’s cold-blooded,” Marichal said. “When he’s on the mound, he dominates everybody — everybody.”

Once Bumgarner’s initial postgame duties on the field were complete, he removed his black cap and tipped it in several directions to the sellout crowd, then offered a wave to the frenzied faithful in orange chanting their would-be World Series MVP.

“Clayton who? MadBum!” one man yelled as he exited AT&T Park in reference to Clayton Kershaw of the rival Dodgers.

It’s true. Bumgarner is the one who has proven himself on the October stage, now drawing comparisons to some of the best pitchers ever this time of year — October aces Bob Gibson, Sandy Koufax, Curt Schilling.

“Very humbling,” said Bumgarner, who improved to a remarkable 4-0 in four World Series starts with an 0.29 ERA.

The fans are sure letting it be known MadBum is the “M-V-P! M-V-P!” and Bumgarner seems the logical choice if the Giants can win one more in Missouri. He outdid his own dazzling performance from Game 1 last week with a sensational start Sunday at AT&T Park, where he hasn’t always been his best while pitching better on the road.

“It’s Oct. 26 and he’s as strong as he was in May,” catcher Buster Posey said.

And this October: 12 hits over 31 innings with 27 strikeouts.

“That was pretty cool, actually,” Bumgarner said. “It was really neat to hear.”

One thing he doesn’t want to hear are questions about fatigue or a tired arm, or even his high innings count at this stage. The durable, 6-foot-5, 235-pound pitcher from Hickory, North Carolina, swears he can handle it all physically.

San Francisco’s relievers were thrilled they got to watch it and not warm up the way Bumgarner was dealing.

“I’ve never seen a better overall starter’s performance in the playoffs than that,” fellow lefty Jeremy Affeldt said. “He continues to amaze us a little bit. That was a performance I actually became a fan in the ninth. I was really, really happy to say I got to watch that game.”

Who could blame Affeldt?

Bumgarner struck out eight and didn’t walk a single batter. No Royals baserunners reached third base. Bumgarner pitched the first World Series since Josh Beckett did so for the Marlins in the 2003 Game 6 finale at Yankee Stadium.