KANSAS CITY, Mo. >> Alex Gordon took a big rip at a batting-practice fastball, fouled it off badly into the cage, and ducked when the carom nearly hit him in the head.

Gordon let out a huge laugh, and so did a bunch of his Kansas City Royals teammates watching Monday’s workout.

“I can’t believe that just happened, dude,” pitcher James Shields razzed.

It’ll be more frustrating than funny if those are the same awkward swings the Royals and San Francisco Giants take once the World Series begins.

Going into Game 1 on Tuesday night at Kauffman Stadium, both teams will deal with a familiar issue this deep in the postseason: Does an extended layoff translate into rest or rust?

Buster Posey and the Giants zipped through the playoffs, and now will try for their third title in five years. Lorenzo Cain and the Royals zoomed along, reaching the Series for the first time since 1985.

And then, they all got some time off. Almost an eternity, by October standards.

The Royals went 8-0 in the AL playoffs, giving them five idle days before Shields starts the opener. San Francisco went 8-2 on the NL side and had four days to relax before Madison Bumgarner pitches.

“It’s definitely different because we have played so many games over the last 7 1/2, eight months. But you just understand it’s one of those things,” Posey said.

As recent history has shown, hitters can be very vulnerable when they get out of rhythm.

“It affects a bit with your timing, especially when trying to adjust to pitchers,” Kansas City second baseman Omar Infante said. “It’s hard to recover that groove you have.”

The slightly favored Giants and Royals held practices, studied video and checked out scouting reports. But as several teams that stumbled in the World Series after long breaks discovered, nothing can duplicate playing a real game.

Triple Crown winner Miguel Cabrera and Detroit got nearly a week off in 2012, then the Tigers hit a combined .159 and totaled six runs in getting swept by the Giants.

Troy Tulowitzki and the Colorado Rockies rushed into the 2007 World Series, waited a week and got outscored 29-10 in Boston’s sweep.

A year earlier, Magglio Ordonez and the Tigers looked so powerful in the playoffs, but fell apart a week later and hit only .199 in a five-game loss to St. Louis.

Infante played on both of those Detroit teams that got wiped out. He actually excelled in 2012, hitting .333.

“It’s a short series, you need some luck. We lost four in a row and they were coming from playing seven. In this series, I think both teams are even,” he said.

Royals reserve Raul Ibanez, who’s enjoyed postseason success in the past, said “determination and will” carry players in the fall. Yet the timing and confidence that lifts them for so long can be lost in a hurry.

All of a sudden, a ball that might’ve been a solid double becomes a soft fly. A line drive up the middle turns into a foul ball straight back. A big hit winds up a great catch.

Just like that, a magical touch is missing, and can’t be recaptured until it’s too late.

Royals catcher Salvador Perez hooted at himself after a popup and an easy grounder in BP on Monday, and changed bats for his next round. He homered on his final swing.

“When you’ve been playing for seven or eight months, it’s nice to have an off day every now and then. But when you do have those workout days where you just go in and hit BP and take grounders and stuff, you try to keep it as much like game day as possible,” Giants first baseman Brandon Belt said.

Royals designated hitter Billy Butler said he didn’t see the five-day break being a detriment.

“Hey, they’ve had four days off. That’s the way you look at it. They played one day later than we have — they’ve had a layoff, too,” he said.

“I don’t know if it’ll play any factor. It definitely won’t be the reason if we go out there and don’t win tomorrow,” Butler said.

Shields and Bumgarner seemed unconcerned.

This will be Shields’ first start since Oct. 10 in the AL Championship Series opener against Baltimore.

“I think this late in the year almost too much throwing is too much,” he said. “So I’ve just kind of rested my body up for tomorrow.”

Bumgarner has already thrown 249 innings this year, including four postseason outings. He was the NLCS MVP, and started last Thursday when the Giants closed out St. Louis.

“Honestly, I feel the best I’ve felt all year for the last probably two months,” the lefty said.