It’s only four games in a 162-game schedule. But it’s Red Sox versus Yankees, in a series starting Thursday night at Fenway Park.

Yes, they are longtime rivals, but this isn’t just for old times’ sake. This season, both teams are on pace to win more than 100 games.

One of them will win the American League East. The other will play in the stressful wild-card game. Assuming the East champion has the best record in the league, it will play the wild-card winner in a division series.

So, as they did in 2003 and 2004, the Red Sox and Yankees could meet in the playoffs. But unlike those years, when the two teams went seven games in the American League Championship Series, the division series is only best-of-five.

Want to know what that might be like? Watch the four-game series this week.

And that’s just the start. In August and September, almost 20 percent of Boston’s schedule will be against the Yankees. They meet again for three games Sept. 18-20 in New York, followed by a season-ending series at Fenway Park on Sept. 28-30. While Red Sox and Yankees fans are rooting for their team to clinch the division title before then, the rest of baseball fandom wants it to come down to that last series.

Boston may have the bragging rights over the past five seasons (three AL East titles and one World Series trophy to New York’s two wild-card entries), but last year signaled that the teams were evening out. Boston won the division but was bounced in the first round of the playoffs, while the Yankees reached the ALCS.

Since then, New York General Manager Brian Cashman and Red Sox President Dave Dombrowski have tried to outmaneuver each other.

Boston fired John Farrell and hired Alex Cora as manager. New York fired Joe Girardi and hired Aaron Boone.

The Yankees traded for a big bat, landing the Marlins’ Giancarlo Stanton.

The Red Sox countered by signing free agent slugger J.D. Martinez.

Now come the moves before Tuesday’s nonwaiver trade deadline.

Boston acquired right-handed hitter Steve Pearce from Toronto (essentially replacing the released Hanley Ramirez) on June 28. Pearce has a career .855 OPS against left-handed pitching (1.063 this year). And, oh, he hits well against the Yankees (career .900 OPS).

Then things got busy last week.

New York traded with Baltimore for left-handed reliever Zach Britton, who has not allowed an earned run since June 27. His Yankees debut Thursday was a 10-pitch, 1-2-3 inning with a strikeout. Coming off an Achilles tendon injury, Britton is looking like his old self. Not good news for Boston, which has managed just eight hits and one run off Britton over three seasons (111/3 innings).

The next day, Dombrowski traded for Rays right-handed starter Nathan Eovaldi. Injuries and ineffectiveness required a shoring up of the rotation, although the bullpen remains a concern.

On Thursday, the Yankees acquired left-hander J.A. Happ from Toronto. He struggled in July, but he pitches well against Boston (7-4, 2.98 ERA), including a 0.84 ERA in two starts this year. On July 12, he gave up five runs in one inning to Boston, but all were unearned, as an error prolonged the inning. A tiring Happ gave up the infamous two-out, 13-pitch grand slam to Mookie Betts.

But Happ usually handcuffs the Red Sox. That’s not surprising, because Boston’s batting average against lefties is .259, as opposed to .272 against right-handers. Left-handed pitchers can dominate Boston (see Oakland lefty Sean Manaea’s no-hitter in April).

While both teams are dominating the competition, neither is without problems.

The Yankees’ latest issue is Aaron Judge, who suffered a cracked bone in his right wrist after being hit by a pitch on Thursday. The Yankees say Judge will be out for three weeks, but who knows? A wrist injury can linger, especially for a power hitter. How important is Judge? Besides hitting 26 home runs, he’s been deadly against the Red Sox this year – batting .455 with four home runs in nine games.

Adding to Judge’s injury is the absence of another slugger, catcher Gary Sanchez, because of lingering groin muscle problems.

For the Red Sox, the bullpen issues remain. Once a strength, the relievers are showing cracks, with few trusted options for Cora. The assumption is that Dombrowski is not done dealing.

New York’s starting rotation is an issue, even with the addition of Happ. But the Yankees have far-and-away the best relief corps in the majors, with a 2.78 ERA and a 1.09 WHIP. And they just added Britton. Who needs a starter to go deep when you have Britton, Dellin Betances, Chad Green, Jonathan Holder, David Robertson, Chasen Shreve, Adam Warren and Aroldis Chapman?

With those arms, can the Yankees catch the Red Sox? Their remaining 10 meetings – starting with the four-game series coming up – is likely to determine that.

Kevin Thomas can be reached at 791-6411 or:

kthomas@pressherald.com

Twitter: ClearTheBases

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