Four-man outfields. High-tech anti-spying rules. A starting pitcher facing just one batter in a playoff game.

But beyond all the shifts, analytics and social media outreach, here’s the best way to tell Major League Baseball has zoomed into a new era: There’s not a single active player left from the 20th century.

Adrian Beltre and Bartolo Colon were the last, the Elias Sports Bureau said. And with all 30 teams set to play Thursday – from Bryce Harper’s home debut at Citizens Bank Park to Mookie Betts and the champion Boston Red Sox visiting Seattle – this year MLB becomes the first of the four major sports without someone still around who played in the 1900s.

Already this season, the great Ichiro Suzuki has retired, done at 45 after two hitless games last week as the Seattle Mariners swept Oakland at the Tokyo Dome.

“I really wanted to play until I was 50, but I couldn’t do it,” he said.

Yankees lefty CC Sabathia says it’s his last year, and so does Giants Manager Bruce Bochy.

But youth springs eternal. Vladimir Guerrero Jr., Fernando Tatis Jr. and Eloy Jimenez lead a strong rookie crop of boppers who might stick around for a while.

After a long winter of waiting, it’s time to play ball.

“Opening Day, since I was a kid, I feel like it’s a celebration of our sport, so it’s something I always look forward to,” Yankees Manager Aaron Boone said.

A look at the lineup going into Thursday:

MARQUEE MATCHUPS
Jacob deGrom, fresh off a big contract boost from the New York Mets, starts against Washington ace Max Scherzer at Nationals Park. DeGrom earned his first Cy Young Award last season, and three-time winner Scherzer finished second. It’s a similar duel at Tropicana Field – AL Cy Young winner Blake Snell of the Rays faces runner-up Justin Verlander and the Astros.

DANDY DEBUTS
Harper takes his first swings since signing a $330 million deal with the Phillies. Harper has five career home runs on Opening Day, tied with Albert Pujols and Ian Kinsler for most among active players, and will take on the NL East champion Braves in the first Sunday Night Baseball matchup on ESPN. Those games will start an hour earlier this season.

Machado starts up with San Diego, Paul Goldschmidt is with St. Louis, Robinson Cano got traded to the Mets, Nelson Cruz swings for Minnesota and the excitable Yasiel Puig is in Cincinnati.

SKIPPING ALONG
Brandon Hyde takes on the daunting task of handling the 115-loss Orioles. He’s among six new managers – Hyde, Charlie Montoyo (Blue Jays), David Bell (Reds), Rocco Baldelli (Twins) and Chris Woodward (Rangers) are first-timers. Brad Ausmus was hired to replace longtime Angels skipper Mike Scioscia.

FINE FORECASTS
A year after a bunch of early snowouts and 54 total postponements – the most since 1989 – no blizzards are on the radar. It could be rainy in Kansas City and perhaps Oakland, but it’s supposed to be sunny at Dodger Stadium and several other sites.

EXTEND THEIR SUCCESS
Chris Sale, who struck out Machado to end the World Series and seal Boston’s fourth crown in 15 seasons, starts the opener for the 108-win Red Sox. Sale, Trout, Verlander, Goldschmidt and Rockies third baseman Nolan Arenado were among the stars whose teams locked them with rich, long-term deals.

But not every big name got a big contract – All-Star closer Craig Kimbrel and former Cy Young winner Dallas Keuchel went into Opening Day without jobs.

A WORLD, AND A SERIES
After opening in Japan, MLB crosses the pond for the first time when the Yankees and Red Sox play twice at London’s Olympic Stadium in late June. There are two sets in Monterrey, Mexico – Cardinals-Reds in April and Astros-Angels in May. Also, there’s a Tigers-Royals matchup in Omaha, Nebraska, as part of the College World Series festivities in June, and a Cubs-Pirates game in Williamsport, Pennsylvania, in August to go along with the Little League World Series.