What Is MLB's ABS Challenge System? How Baseball's Newest Mechanism Works

Updated Oct. 21, 2026 1:58 p.m. ET

For the first time ever in World Series history, we'll have the Automated Ball-Strike (ABS) Challenge System in use. And when a player calls to challenge a pitch and an image of the strike zone pops up on your screen, you'll want answers — which we have.

Here's what to know about the ABS Challenge System:

What Is the ABS Challenge System?

The ABS Challenge System, which was introduced to MLB this season and was previously used in the minor leagues and in the 2025 MLB All-Star Game, is a way for players to challenge the home plate umpire's call of a ball or strike. Imagine if Ty Cobb had this power!

How Does the ABS Challenge System Work?

A player has to immediately tap their helmet/cap to challenge the call of a ball or strike. Failure to promptly do so will lead to a request being denied.

After a request is acknowledged, the stadium videoboard will promptly depict a graphic simulation of the pitch with it showing if the challenged pitch was in the strike zone. 

Teams get two ABS challenges per game and maintain those challenges if a call is overturned. That said, teams get an extra challenge per inning if the game goes to extra innings.

Who Can Use the ABS Challenge System?

The ABS Challenge System gives MLB players a way to contest the home plate umpire's call of a ball or strike. (Photo by Ryan Sun/Getty Images)

Only three people on the field can request a challenge: the batter, pitcher and catcher. Coaches aren't able to challenge a pitch.

ABS Challenge System Affecting The Playoffs?

The ABS Challenge System has corrected countless calls, and it actually helped end a 2026 playoff game.

In Game 2 of the National League Wild Card Series, the Atlanta Braves had the tying and winning runners on the basepath in the bottom of the 10th inning with two outs. Then, after a ball was called to put Braves pinch hitter Dominic Smith in a 1-2 count, Philadelphia Phillies right-hander Andrew Painter challenged the pitch, and it was overturned for strike three.

The ABS challenge secured a Phillies win, keeping their season alive for one more day. 

How To Watch The 2026 World Series

The 2026 World Series between the Tampa Bay Rays and Milwaukee Brewers, who are each seeking their first championship triumph, can be exclusively viewed on FOX, beginning on Oct. 23.

Game 1: Friday, Oct. 23

  • Rays at Brewers (8 p.m. ET)

Game 2: Saturday, Oct. 24

  • Rays at Brewers (8 p.m. ET)

Game 3: Monday, Oct. 26

  • Brewers at Rays (8 p.m. ET)

Game 4: Tuesday, Oct. 27

  • Brewers at Rays (8 p.m. ET)

Game 5*: Wednesday, Oct. 28

  • Brewers at Rays (8 p.m. ET)

Game 6*: Friday, Oct. 30

  • Rays at Brewers (8 p.m. ET)

Game 7*: Saturday, Oct. 31

  • Rays at Brewers (8 p.m. ET)

* - if necessary