That's because of an apparent impasse between Time Warner and Comcast SportsNet, the provider of Celtics games, college basketball and other sports programming.
"We are in active negotiations" with Time Warner, said Comcast spokesman Skip Perham.
The question, as it always is, concerns money. The cable company is being asked to pay what it deems too much for the programming.
"They are demanding a 112 percent increase in what we paid for programming in 2007," said Peter Taubkin, Time Warner's vice president of government relations and public affairs. "They're developing a rate not in line with other regional sports networks."
Perham said the rate increase described by Time Warner was not accurate.
"I can't really address the speculation of what the percentage is," he added.
Time Warner isn't the only company having difficulties with Comcast. According to the Web site multichannel.com, DirecTV and Comcast are involved in a license-fee dispute for Comcast SportsNet New England and for Comcast SportsNet Bay Area.
"In New England, Comcast wants 25 percent more," Derek Chang, DirecTV's executive vice president of content strategies, is quoted as saying in the article.
Comcast SportsNet and Time Warner have been in negotiations since the most recent contract expired at the end of 2008.
For their part, Time Warner blames the cost increases on the increased rights fees programming sources have to pay teams and leagues for programming.
"They need to make better deals for sports rights and not pass those increases onto cable customers," said Taubkin.
From Comcast's point of view, the network has improved the quality of its telecasts and improved its programming. Currently, all Celtics games on CSN are broadcast in high definition. The network also has new programming related to the Celtics, along with carrying college sports.
Perham said that negotiations were ongoing, while Taubkin said Time Warner has asked for an extension beyond today's deadline, so tonight's Celtics-Hawks game can be seen.
"If they pull the channel from our lineup, it's their decision, not ours," added Taubkin.
After tonight, there are five more regular-season Celtics games this year. If there is no immediate agreement, three of the five games would not be seen. The April 12 game against Cleveland is on ABC, while the game on April 14 will also be seen on TNT.
Comcast will carry first-round playoff games, along with whatever games might be picked up by TNT, ABC or ESPN. After that, CSN will not broadcast games, but will have extensive pre and post-game programming wrapped around telecasts.