National Football League (NFL) team owners and players will allow another week for talks on a new agreement involving pay and other conditions.
The parties had already extended talks for 24 hours until midnight Friday (0500GMT) but have accepted they will not reach a deal within that timeframe.
The main sticking point is how to distribute the league's $9bn (£5.6bn) in annual revenues.
If not resolved, the row could delay the 2011 season.
The talks, which cover wages, drug testing, pension benefits, and plans to increase regular-season games from 16 to 18, had reached their 11th day of negotiations.
Players for the NFL's 32 teams currently receive 60% of the $9bn revenues, something the clubs' owners see as too generous.
The NFL, one of the richest sporting series in the world, takes $1.3bn for costs but it says these have risen steeply since the previous deal was struck in 2006 and it wants its take to rise to $2.3bn, something that would mean less money for the players.
The dispute could have far-reaching consequences.
The players' association, the NFLPA, may decide to "decertify", in effect renouncing its status as a union and becoming a trade association instead.
This would mean that arrangements made in the past through collective agreements between the union and the NFL would no longer be immune to competition law, and could be challenged in the courts.
Such arrangements are central to the way the NFL works.
They include the salary cap, which limits the amount clubs can spend on wages, and the draft system which ensures the weakest clubs have first refusal on the best players coming through the college system.
These measures mean that the richest clubs cannot simply buy up all the best players, and ensure that the league remains competitive.
But in the absence of a collective agreement, they could be deemed illegal, and expose the NFL to potentially damaging lawsuits.