LeBron James, the superstar forward for the NBA's Cleveland Cavaliers, might be the biggest star in all of American sports. He's got 21.7 million Twitter followers and earned an estimated $44 million this year in endorsements alone. But his most ardent fans might not be interested in tweets or high-top sneakers -- they're grandmothers in the Cleveland area, cheering on their homegrown hero, as much for his athletic talents as for his generosity to the local community.

The LeBron James Grandmothers' Fan Club has drawn a fair bit of attention since a recent profile in the Wall Street Journal and an ESPNW article and video about them. The Akron, Ohio-based club has simple membership rules: You must be a grandmother (or great-grandmother) and you must love James. And when Game 3 of the NBA Finals between the Cavaliers and Golden State Warriors takes place Tuesday night, the 200-plus grannies will surely be showing him some love at their watch party.

75-year-old retiree Alder Chapman started the club with a few LeBron-loving friends in 2006, about three years after the Cavs selected James No. 1 overall in the 2003 NBA Draft. The grannies in the club, some of whom have been following the star forward since his high school days, all think of James like a grandson. 

"We love him," Chapman, who has six grandchildren, told ESPNW. "He just feels like one of ours."

The LeBron James Grandmothers' Fan Club website -- indeed, the grannies have a site -- cites James' generosity in the community and lists some of their own community activities. A main message on the site: "His God-given gift of basketball brings us so much joy and makes our hearts tick." The grandmothers' joy was on display for Game 4 of the Eastern Conference Finals, when the James-led Cavaliers punched their ticket to the 2015 Finals. The group -- after some members put down their knitting supplies – screamed "L-B-J" in a restaurant plastered with James-related newspaper clippings, reported the Wall Street Journal. 

The club -- which usually meets monthly but has met more often during the playoffs -- even remained loyal to James when he left Cleveland for Miami in 2010. The  grannies told the Journal that the club is a James fan club, not a Cavaliers fan club. And when James came back to Cleveland before this season, he acknowledged his large group of grandmothers.

“I heard I got a grandmas’ club now with 200-plus grandmas,” he said at a press event last summer, according to the Wall Street Journal. “So I’m hitting all ranges.”

With the NBA Finals series tied at 1-1, James is three wins away from bringing the beleaguered city of Cleveland its first professional sports title in more than 50 years. You can bet the grandmothers will be watching intently. "If you want to see a real Cavs fan, come to one of our game watches," Chapman said to ESPNW.