Patrick McCaw was nodding off July 5 in the backseat of a GMC Yukon when his iPhone lit up with a text from an unfamiliar number. Drained from packing his life into suitcases, the Warriors’ bleary-eyed rookie considered ignoring the message.

“Then I saw it was from Kevin Durant,” McCaw recalled. “I just froze for like 20 minutes. I just read it. I kept reading it over and over.”

A day earlier, Durant had rocked the NBA by announcing his intention to sign with Golden State. In the wake of this life-changing decision, as talking heads around the country vilified him for making the easy move, the seven-time All Star promised to take McCaw under his wing.

The two had not met. But in that moment, staring at his iPhone screen, McCaw recognized that he was in an enviable situation. A second-round pick from UNLV, he will study under the player he idolized long before Durant sponsored McCaw’s high school team.

“I feel like I was the No. 1 pick,” said McCaw, who heard 37 names called before his on draft night. “You couldn’t tell me otherwise.”

Unlike Durant, who has been tracked for greatness since middle school, McCaw was overshadowed by his peers as a teen. A rail-thin shooter with a precariously high dribble, the St. Louis native was a three-star prospect with limited interest from Power 5 conference programs. McCaw’s AAU team, the Chicago-based Mac Irvin Fire, featured five players ahead of him on recruiting boards.

Still, he had enough of a reputation for basketball factory Montrose Christian to offer the rising senior a roster spot for the 2013-14 season. At the time, all McCaw knew about the small Baptist school in Rockville, Md., was that it was Durant’s alma mater.

In the late 1990s, with enrollment declining, officials had viewed basketball as an opportunity to keep Montrose Christian afloat. The Mustangs stockpiled elite recruits, played a national schedule and became a mainstay in USA Today’s Super 25 rankings. (The school has since reversed course on that strategy, announcing plans last year to de-emphasize basketball.)

Back in March 2006, though, the Mustangs participated in what some bill as the greatest high school basketball game of all time. A Durant-led Montrose Christian team toppled an unbeaten Oak Hill Academy squad boasting future NBA players Michael Beasley, Ty Lawson and Nolan Smith on a buzzer-beater.

By the time McCaw arrived on Montrose Christian’s suburban campus, coaches were selling players on being the next Durant. A 2010 NBA commercial showed a young Durant sitting on a classroom table in a Mustangs jersey. In case they forgot about the school’s connection to the face of the Oklahoma City Thunder, coaches often reminded players that their uniforms were the result of Durant’s generosity.

“We were always hearing about what he did for Montrose Christian, how great of a player he was and how he was giving to us,” McCaw said. “Even though he went to the high school, he didn’t have to show us love like that. We all appreciated his character.”

McCaw, who guided Montrose Christian to a National Christian School Athletic Association Division I title in 2014, was the the most lightly touted prospect in a five-man UNLV recruiting class ranked No. 4 nationally. As a sophomore last season, he led the Rebels in points, assists, steals, three-pointers and minutes.

McCaw risked falling out of the first round, and the guaranteed contracts that brings, to declare for the draft. Surrounded by friends and family June 23 at his St. Louis home, he broke down in tears when he finally heard his name called.

Twenty minutes later, when he learned that Milwaukee had traded his rights to Golden State for $2.4 million, McCaw had a tough time believing his luck. It showed that the Warriors, fresh off their second straight Finals appearance, saw him as more than just another late draft pick. They soon signed him to a guaranteed two-year deal.

As the only player on the Summer League roster under contract with the NBA club, the 6-foot-7, 185-pound combo guard led Golden State with 15.8 points per game on 46.7 percent shooting (38.2 from three-point range) in Las Vegas. McCaw’s size and versatility gives him a shot at cracking a deep backcourt rotation.

“I think he has a chance to contribute,” head coach Steve Kerr, whose team opens training camp Sept. 27, said last month. “It’s hard to do as a rookie, but I could see throwing him out there and him doing well.”

McCaw broke away from drills Tuesday morning at the Warriors’ practice facility to formally introduce himself to Durant. The 2013-14 NBA MVP kept the conversation light with his 20-year-old protege, asking about McCaw’s recent move to Jack London Square.

“It’s just crazy that I’m on a team with those types of players,” McCaw said. “It’s just a blessing.”

Connor Letourneau is a San Francisco Chronicle staff writer. Email: cletourneau@sfchronicle.com Twitter: @Con_Chron