This early in the season, just about every MLB division race is wide open. As it stands now, the Dodgers and Phillies are the only teams to lead a division by more than two games. As such, every divisional series still matters at this juncture, and this week has a couple of big ones.

The D-backs will travel to face the Dodgers, and the Cardinals will host the Cubs, with both of those divisional rivalries highlighting our series to watch for the week of May 20.

D-backs (22-25) at Dodgers (32-17)
3 games (Monday-Wednesday)

Head to head: The Dodgers took two out of three games over the D-backs in Los Angeles earlier this season. Last year, the Dodgers went 8-5 against Arizona in the regular season, but the D-backs got revenge in a shocking 3-0 NLDS sweep.

Storyline: How legit is the Dodgers’ new-and-improved starting pitching? Los Angeles’ starters had a 25.07 ERA in last year’s NLDS -- worst by any team in a playoff series (min. 2 games) since earned runs became an official stat in 1913. But the team loaded up by acquiring the likes of Tyler Glasnow and Yoshinobu Yamamoto in the ensuing offseason -- the latter of whom already threw six scoreless innings against the D-backs earlier this year.

Watch out for: Joc Pederson. The California native and 2010 Dodgers first-round Draft pick played seven seasons with the team, culminating in the 2020 World Series title. Though he has not performed well against the Dodgers in the past (.180 batting average, .582 OPS), he’s had a stellar 2024 season thus far, currently holding a career-high .978 OPS.

Mariners (25-22) at Yankees (33-15)
4 games (Monday-Thursday)

Head to head: These two teams have not played each other in 2024. Last year, the Yankees went 4-2 against the Mariners, taking two of three games in both New York and Seattle.

Storyline: This is a possible playoff preview of two current division leaders, and it will be a pristine pitching matchup. The Mariners’ rotation has lived up to its preseason status as the best in MLB, but it’s actually the Yankees who lead MLB by allowing 3.21 runs per game.

Watch out for: Anthony Volpe. On an offense led by the likes of Aaron Judge and Juan Soto, it’s easy for the 23-year-old shortstop to fall under the radar, but he’s vastly improved in his second MLB season. His batting line has moved from .209/.283/.383 as a rookie to .270/.341/.429 this year.

Rangers (24-24) at Phillies (34-14)
3 games (Tuesday-Thursday)

Head to head: These teams have not faced off this season. Last year, the Rangers swept the Phillies in Texas in a three-game series to open the season.

Storyline: The World Series matchup that never was. Last year was the first time in MLB history that two different teams won at least seven of their first eight playoff games, but the Phillies proceeded to blow a 2-0 NLCS lead to Arizona to prevent a Texas-Philadelphia World Series. This year, though, the Phillies have won or tied their last 14 series, one shy of their franchise record (min. 2 games in each series), according to the Elias Sports Bureau.

Watch out for: Bryson Stott. The 26-year-old middle infielder had a rough start to the season, holding a .210/.275/.284 batting line through April 27. In 18 games since, though, he’s been “A-O, A-O-K” with a .382/.532/.709 line, with the Phillies going 14-4 in those games.

Brewers (27-19) at Red Sox (23-24)
3 games (Friday-Sunday)

Head to head: These teams have not played each other in 2024. Last season, the Red Sox took two of three games in Milwaukee in April.

Storyline: The Brewers’ offense against the Red Sox’s pitching. This will be a classic strength-on-strength battle. The Brewers average 5.11 runs per game, third in MLB behind only the Phillies and Dodgers. But even with Garrett Whitlock on the IL, Boston’s starting pitching has been fantastic, ranking second behind the Phillies with a 2.70 ERA.

Watch out for: Both starting catchers. William Contreras’ dominance this season has been well-documented, and he’s on pace for career highs in just about every relevant statistic. But in the other dugout, Connor Wong has more quietly been among MLB’s elite catchers. He leads MLB (min. 100 PA) with a .354 batting average, though Contreras isn’t far off at .341.

Cubs (26-22) at Cardinals (20-26)
3 games (Friday-Sunday)

Head to head: These teams have not played each other yet this season. Last year, the Cubs went 8-5 against the Cardinals.

Storyline: The rivalry continues. Entering this series, these teams have coincidentally faced off exactly 2,500 times in the regular season, the fifth-most of any pair (behind Cubs-Pirates, Cardinals-Pirates, Giants-Dodgers, Phillies-Braves). The Cubs are 1,267-1,214 in those games, along with 19 ties.

Watch out for: Michael Busch. After playing in 27 games with the Dodgers in 2023, Busch was traded to the Cubs, and he’s made an immediate impact. Still maintaining his rookie eligibility, Busch has seven home runs, a .456 slugging percentage and a .785 OPS this season. And for what it’s worth, these will be Busch’s first MLB games at St. Louis’ Busch Stadium.