Both teams have clinched. Neither knows where it's playing next week.
Updated Friday, Sept. 25 at 5:12 p.m. ET with Game 1 results and Game 2 lineups.
Boston beat Chicago 4-3 in the opener of a doubleheader at Fenway Park, moved up because of a nor'easter forecast to hit New England over the weekend. Sunday's game was rescheduled into Friday, and Game 2 was pushed from 6:05 to 5:35 p.m. ET.
Boston took Game 1
Chicago led 3-0 after two. Tyrone Taylor doubled home Seiya Suzuki in the first, and Miguel Amaya doubled home two in the second.
Boston got it back in the fifth on a Roman Anthony double and an Adley Rutschman two-run single off Caleb Thielbar. Anthony tripled in the seventh and scored on a Connor Wong double for the lead.
Greg Weissert got the win, Aaron Civale the loss, Raymond Burgos the save. Anthony finished with a double, a triple and two runs.
Alex Bregman, back in the lineup two days after taking a foul ball to the face while on deck, struck out looking in the seventh and lost the challenge.
Game 2
Friday, Sept. 25 — 5:35 p.m. ET
Fenway Park
TV: NESN in New England, Marquee Sports Network in Chicago
Streaming: MLB.TV and Fubo, subject to local blackout
Radio: WEEI 93.7 in Boston, with Spanish on WCCM 1490 AM and WESX 1230 AM. 104.3 The Score in Chicago.
Probables: LHP David Peterson (9-8, 4.96) for Chicago, RHP Brayan Bello (6-7, 4.49) for Boston.
Chicago: Pete Crow-Armstrong CF, Seiya Suzuki RF, Michael Busch 1B, Michael Conforto DH, Ian Happ LF, Nico Hoerner SS, Pedro Ramírez 2B, Carson Kelly C, Matt Shaw 3B.
Boston: Roman Anthony RF, Jahmai Jones LF, Wilyer Abreu DH, Trevor Story SS, Nick Sogard 1B, Andruw Monasterio 3B, Jarren Duran CF, Isiah Kiner-Falefa 2B, Connor Wong C.
What's at stake
Chicago is 88-72 and holds the second National League wild card. San Diego is 89-70 and a game ahead, and the difference is home field — the fourth seed hosts the fifth in a best-of-three, and the higher seed hosts every game.
The Cubs are 46-35 at Wrigley and 42-36 on the road.
Boston is 86-74 and holds the second AL wild card. The Red Sox are 39-39 at Fenway and 46-35 on the road, the only playoff team in either league better away from home.
Countries on the field
Boston's roster runs through ten countries.
Wilyer Abreu, Andruw Monasterio, Willson Contreras, Ranger Suárez and Jedixson Paez are Venezuelan. Abreu and Monasterio both start Game 2. Brayan Bello, who pitches it, is Dominican. Ceddanne Rafaela is from Willemstad, Curaçao. Aroldis Chapman and Johan Oviedo are Cuban. Masataka Yoshida is Japanese. Raymond Burgos, Jovani Morán and Eduardo Rivera are Puerto Rican. Tyron Guerrero is Colombian. Tsung-Che Cheng is from Taiwan. Curtis Mead is Australian, from Adelaide.
Chicago starts Seiya Suzuki, from Tokyo, and Pedro Ramírez, the Venezuelan infielder. Miguel Amaya, the Panamanian catcher from Chitré, doubled home two runs in Game 1.
Who's hitting
Crow-Armstrong has 45 home runs, the most in the majors, with 107 RBIs, 40 stolen bases and a .949 OPS. Seiya Suzuki has 26 homers.
Abreu has 24 home runs and 74 RBIs for Boston. Jarren Duran has 20 homers and 21 steals. Ceddanne Rafaela is hitting .282.
Two long injury lists
Chicago has seven pitchers on the 60-day list — Justin Steele, Cade Horton, Ben Brown, Porter Hodge, Shelby Miller, Hunter Harvey and Phil Maton, most with elbow or arm problems. Kevin Gausman is day-to-day with a shoulder issue.
Boston has six on the 60-day: Garrett Crochet, Tanner Houck, Kutter Crawford, Johan Oviedo, Zack Kelly and Triston Casas. Masataka Yoshida is on the 10-day with a hamstring, Curtis Mead with a hand. Willson Contreras is day-to-day.
The rest of the weekend
The final NL wild card is still open. Philadelphia is 87-72 and Arizona 85-74, and the D-backs finish the season in San Diego while the Phillies host Tampa Bay.
The AL West is tied. Houston and Texas are both 79-80 with three games left — the Astros against the Athletics, the Rangers against the Twins. Only the division winner gets in, and Houston holds the head-to-head tiebreaker at 9-4.
Cleveland and the White Sox are both in, playing for the Central title and the first-round bye that comes with it.
Wild card series begin Sept. 29. Division series begin Oct. 3.