Major League Baseball will announce Friday that it will implement at least three significant pace-of-play rule changes, according to a report.

The rules include mandating that managers stay in the dugout during replay challenges, that hitters keep at least one foot in the batter's box during at-bats and a prompt return to play after television commercial breaks, according to sources.

The league established a pace-of-game committee in September aimed at making recommendations to speed up games, which grew to a record average of 3 hours, 2 minutes in 2014, up from 2:33 in 1981.