Another day ran off the clock on talks to salvage opening day of the MLB when locked-out baseball players proposed what they considered a small move forward in drawn-out labour negotiations and management termed it a third straight step backward.

Management again proposed a federal mediator enter the negotiations, but the union immediately turned down that idea, leaving MLB on track to lose regular-season games to a labour dispute for the first time since 1995.

Less than a week remains until the sides reach what management says is a Monday deadline for a deal that would allow the season to start as scheduled on March 31.

Players have not said whether they accept that timeframe, and there remains a sense both sides are awaiting more time pressure to force more major moves by the other.

Still, the sides agreed to meet for a third day in a row on Thursday (AEDT), the 84th day of the second-longest work stoppage in baseball history.

Players made a tiny shift toward management on Tuesday on their proposal for increased salary arbitration eligibility, lowering to the top 75 per cent by service time among the group with at least two seasons in the majors but less than three.

The union last week came off its prior demand that all two-year players be eligible - the level from 1974-86 - and instead proposed the top 80 per cent by service.

Teams have said any movement in this area is not significant because management maintains it will never agree to any increase.

Players took a step back from clubs in their proposal for major league minimum salaries, which had been for $US775,000 this season with $US25,000 annual increases during a five-year deal to $US875,000 in 2026.

The union instead proposed a $US30,000 rise each year, to $US895,000 in the final year.

MLB has proposed a rise from $US570,500 to $US630,000 and then by $US10,000 annually, to $US670,000 by 2026.

The union calculated its movement for the day as $US25 million over five years.

The sides had met on consecutive days just once before, on January 24 and 25.

There was no movement on the biggest issue: luxury tax thresholds and rates.