Now that we’re past the All-Star break and into mid-July, MLB’s already tight playoff races are only going to heat up more. The sport has no shortage of surprise playoff contenders, including but not limited to the Orioles, Rangers, D-backs and Reds, so the second half of the season will serve as a litmus test for how legitimate these upstart teams are.

All four of these teams will be put to the test in high-profile matchups this week. Among other key showdowns, Cincinnati will face Arizona in a battle of exciting young NL teams, while Texas will host Tampa Bay in a battle for AL supremacy.

Those matchups, and more, are included in our five series to watch during the week of July 17:

Dodgers (53-39) at Orioles (57-35)
3 games (Monday-Wednesday)

Head to head: These teams last played in September 2019, when the Dodgers won two out of three games in Baltimore.

Storyline: This is a showdown of playoff contenders whose lineups were built in vastly different ways. Baltimore is led by a slew of strong recent Draft picks (Adley Rutschman, Gunnar Henderson, Austin Hays, Cedric Mullins, Ryan Mountcastle), while the Dodgers are headlined by big-name free agent or trade acquisitions like Mookie Betts, Freddie Freeman and J.D. Martinez.

Watch out for: Mookie Betts. Here’s Betts’ OPS by month this season: .781 from March-April, .958 in May, 1.037 in June and 1.381 in July (to go with five homers in 11 games). It’s not too hard to sense the pattern here, and if that pattern continues, Betts may catch up to Ronald Acuña Jr. in the MVP race.

Rays (60-36) at Rangers (55-39)
3 games (Monday-Wednesday)

Head to head: This will be the second series between these two teams this season, after the Rays won two of three games at home in June.

Storyline: Who’s the best of the best in the AL? This is a battle of MLB’s top two teams in run differential, with the Rangers (+159) just ahead of the Rays (+152). It also is a showdown of MLB’s top scoring offense (Texas, 5.86 runs per game) against its top defense (Tampa Bay, 3.83 runs allowed per game). By nearly any metric, these squads have excelled, making this a potential playoff preview.

Watch out for: Isaac Paredes. The 24-year-old did not earn All-Star status like several of his teammates, but he’s quietly played a key role in Tampa Bay’s dominant season, ranking second on the team with 17 homers. Two of those came in a June 9 win over the Rangers, which he finished with three hits and six RBIs.

Padres (44-50) at Blue Jays (53-41)
3 games (Tuesday-Thursday)

Head to head: These teams last played in May 2019, when the Padres won two of three games in Toronto.

Storyline: Are MLB.com’s preseason World Series favorites going to turn it around in the second half? If so, the Padres don’t have much time to do so. Only three teams have ever made the playoffs after losing at least 50 of their first 94 games, and none have done so since the 1984 Royals (though, to be fair, MLB's postseason has expanded significantly in recent years).

Watch out for: Vladimir Guerrero Jr. What will the 2023 Home Run Derby champion do for an encore? That remains to be seen, but if his 163 hard-hit balls this season are any indication (second-most in MLB, behind Acuña, via Statcast), he’s going to continue to crush the ball far and often.

D-backs (52-42) at Reds (50-44)
3 games (Friday-Sunday)

Head to head: These teams have not yet faced off this season. In 2022, the Reds went 4-3 against Arizona, including a split of a four-game series in Cincinnati.

Storyline: Which of these surprise teams is legit -- if not both? Arizona hasn’t made the playoffs since 2017, while the Reds haven’t done so in a 162-game season since 2013. But, largely thanks to some elite rookies (Corbin Carroll, Spencer Steer, Matt McLain, Elly De La Cruz), and some aggressive baserunning (these are the NL’s top two teams in stolen bases, with Cincinnati leading MLB), both are having their best season in years.

Watch out for: Ketel Marte. Lost in all the discussion about the D-backs’ young talent is the fact that Marte is having a huge bounce-back year in his ninth MLB season. His 15 home runs are already the second-most he’s ever had in a season (he had 32 in 2019), and his .851 OPS trails only Luis Arraez among qualified second basemen.

Phillies (51-42) at Guardians (45-48)
3 games (Friday-Sunday)

Head to head: These two teams last played in September 2019, when Cleveland won two out of three games at home.

Storyline: Are the Phillies back? You likely remember how their 2022 season went: a 21-29 start, followed by Rob Thomson coming in and turning the ship around, leading to an 87-75 season and an NL pennant. While there’s a long way to go, 2023 looks eerily similar (minus the new interim manager part), as Philadelphia is 26-10 since a 25-32 start.

Watch out for: Bryson Stott. Though his roster is filled with bigger names like Bryce Harper, Trea Turner and J.T. Realmuto, Stott has played a major role in Philadelphia’s aforementioned turnaround. The second-year second baseman has a .328 batting average since June 1, leading a Phillies offense that has averaged 5.21 runs per game over that span.