Tony Clark, the head of the Major League Baseball Players Association, says it will be difficult for players to participate in the 2020 Tokyo Olympics.

Baseball returns to the Olympics after a 12-year absence for the Tokyo Games, which are scheduled July 24 to Aug. 9.

"There are challenges with the schedule, and there are challenges with major leaguers being involved," Clark said.

In 2008, players on Major League 25-man rosters and disabled lists on June 26 were ineligible to play. The United States roster included 17 players from Triple-A, seven from Double-A and college pitcher Stephen Strasburg.

"It doesn't mean that we are not continuing to have dialogue. We have [been] going back. We will [be] going forward. Where we land, I don't know," Clark said. "One of the things we were able to discuss during this round of bargaining were some additional flexibility in the schedule moving forward. Maybe there are some opportunities for a broader discussion than there have been a year ago. We'll have to wait and see. We haven't had that kind of substantive sit-down yet."