Major League Baseball this week will begin testing an automated system that will keep count of balls and strikes. The tests will take place during spring training and could be rolled into regular-season play in 2026.

The first test subjects for this? The Los Angeles Dodgers and Chicago Cubs game on 3:05 p.m. ET Thursday.

Umpires will still squat behind the plate. (After all, who else will give the catcher a new ball after a foul tip?) But the robo-umps will act as an appeals system for batters who think the human ump made the wrong call.

Challenges must be made quickly, though—within one or two seconds of the pitch. Once they’re made, the stadium’s screens will show the arc of the pitch and whether it was in the strike zone when it crossed the plate. If the challenger is right, the count changes and play continues with a slightly red-faced umpire. If the ump was right, the team that lodged the complaint loses one of its challenges (which will be at least two per game).

It does add another psychological layer to the game, even if it could cause delays. Managers will have to time challenges appropriately, and an angry batter could upset the team’s apple cart if they call for one spontaneously.

The rules for the robo-ump aren’t set in stone. After spring training, the league will talk with players to see whether the system is ready for prime time.

This is just the latest rule change for Major League Baseball. In 2023, the league added a 30-second timer between batters and a pitch clock to keep the game moving at a steady pace. Pitchers also only have a limited number of times they can attempt to pick off a base runner. And bases were made bigger as well.