Major League Baseball and the MLB Players Association plan to meet again Tuesday after a Monday bargaining session led to the first sliver of progress between the sides since the league locked the players out Dec. 2, sources told ESPN on Monday.

In the face-to-face meeting, which lasted about two hours, the union offered a broad proposal in which it dropped its request for age-based free agency and significantly cut the amount of revenue sharing it asked the league to funnel away from small-market teams, according to sources.

The day before the lockout, MLB had asked the union to remove three items from its list of desires: changing the six-year reserve period before free agency, lowering arbitration eligibility to two years and adjusting revenue sharing. When the MLBPA declined to do so, negotiations ended and the league implemented the lockout, the sport's first work stoppage in more than a quarter century.

During Monday's meeting, the union rejected three MLB proposals from the first post-lockout meeting between the sides 11 days ago, sources said. MLB offered a formula-based salary system for players between two and three years of service time, a draft-pick reward for success by players who started on Opening Day rosters and a slight tweak to a draft lottery in which all non-playoff teams would be eligible to receive a top-three pick.

The players remained steadfast in a number of their positions Monday, sources said, including raising the minimum salary from $570,500 a year to $775,000, bumping the competitive balance tax threshold from $210 million to $245 million and instituting a draft lottery among non-playoff teams for the first eight picks.

Dropping the request for age-based free agency, which would make some players eligible for free agency before the current six-year standard, helped set the stage for Tuesday's meeting. After requesting smaller-market teams receive $100 million less in revenue sharing in an earlier proposal, the union cut its ask to $30 million, according to sources.

The small meeting of four people from each party included MLB's Dan Halem and the MLBPA's Bruce Meyer, the lead negotiators, as well as longtime reliever and union leader Andrew Miller and Colorado Rockies owner Dick Monfort, who is head of the league's labor relations committee.

Time is quickly becoming a factor in the negotiations, with spring training set to start in mid-February. While a delay of spring training is unlikely to significantly change the trajectory of talks, the specter of losing regular-season games -- which begin March 31 -- is expected to play a role.