With a negotiating deadline just days away, it now appears "likely" that Major League Baseball and the players' association will reach an agreement to expand the playoffs to 10 teams starting this season, sources familiar with the discussions have told ESPN.com.

According to the terms of baseball's new labor deal, the two sides are required to reach an agreement before Thursday or postpone playoff expansion until 2013. However, discussions to resolve numerous scheduling issues have "intensified" in recent days, said one source.

Multiple sources have declined to reveal any details of the talks, but the sides have made enough progress that one source said, "The feeling is now that it's likely that something is going to get done."

Despite commissioner Bud Selig's unabashed push for expanding the playoff field this year, baseball's schedule-makers have been hung up for weeks about how to make expansion work for this season.

With the regular-season schedule already in place, they are faced with the challenge of trying to squeeze two one-game, wild-card playoffs, the Division Series and the League Championship Series -- along with potential tiebreaker games and weather postponements -- into a tight three-week window between the end of the season Oct. 3 and the start of the World Series on Oct. 24.

Those issues will not be a problem in 2013, when the regular-season schedule can be set up to accommodate the larger postseason field. The difficulty with implementing it this year was that negotiations did not begin until after the regular-season schedule already had been finalized.

Under the terms of the labor agreement, there would be two wild-card teams in each league instead of one. And, in order to place more value on finishing first, the two wild cards would play each other right after the season in a one-game, win-or-go-home game. The winner then would advance to play in the Division Series.

As recently as last week, sources were suggesting the two sides hadn't been able to agree on any acceptable postseason-schedule format. However, the increased pace of the discussions since then are a sign that a solution is in sight.

The biggest problem the scheduling experts have faced is trying to fit the best-of-five Division Series into just a six-day window, so the League Championship Series can begin Saturday, Oct. 13. That would mean eliminating at least one travel day in the Division Series, a development that could lead to major travel and game-time issues.

One source said the two sides are still talking because the deal is still "not done," and not all details have been ironed out. But sources are expressing optimism that all of the remaining obstacles can be overcome in time to implement the new playoff format for this year.

Senior writer Jayson Stark covers Major League Baseball for ESPN.com.