NEW YORK (AP) — Major League Baseball has served notice is may circumvent the players union in order to make some rules changes.

Commissioner Rob Manfred says steps are being taken to clear the way to unilaterally change the strike zone, install pitch clocks and limit trips to the pitcher's mound starting in 2018.

The collective bargaining agreement requires baseball to get union approval before making rule changes, unless it gives the union a one-year notice.

Manfred has served notice the league intends to do that.

Union head Tony Clark recently indicated opposition to the proposed changes for this season.

MLB players' union agrees to pitchless intentional walks

NEW YORK (AP) — The players' association has agreed to Major League Baseball's proposal to have intentional walks without pitches this year.

While the union has resisted many of MLB's proposed innovations, players are willing to accept the intentional walk change.

"As part of a broader discussion with other moving pieces, the answer is yes," union head Tony Clark wrote Wednesday in an email to The Associated Press. "There are details, as part of that discussion, that are still being worked through, however."

The union's decision was first reported by ESPN .

Agreement with the union is required for playing rules changes unless MLB gives one year advance notice, in which case it can unilaterally make alterations. Baseball Commissioner Rob Manfred expressed hope Tuesday that ongoing talks would lead to an agreement on other changes but also said clubs would reserve the right to act unilaterally, consistent with the rule-change provision of the sport's labor contract.