A serendipitous stretch of N.B.A. schedule in March allowed Mike D’Antoni to be in the building when his brother Dan coached Marshall University to the school’s first N.C.A.A. tournament berth in 31 years. Mike D’Antoni’s Houston Rockets happened to be in Dallas on the same weekend that Dan’s Thundering Herd won the Conference USA championship game in nearby Frisco, Texas.

“He rejoiced as much as I did,” Dan D’Antoni said.

Dan D’Antoni reciprocated late Tuesday night with some remote cheerleading from a conference meeting in Florida as the Rockets produced the shock of the N.B.A. season by winning a 95-92 grindfest on the Golden State Warriors’ home floor, where the Warriors hadn’t lost a playoff game since Game 7 of the 2016 N.B.A. Finals. Yet Marshall’s coach was adamant that a seat in front of the television is as far as he’s willing to go — for now.

As the elder of the two bench brothers, Dan, 70, has invoked his right to make the rules and challenge Mike, 67, to reach a higher standard before he will consent to becoming an in-person presence on the Rockets’ bandwagon.

“I’ve been to the Western Conference finals a couple times,” Dan D’Antoni said in a phone interview. “I told him you have to get past that and then we’ll come and watch.”