'In My Blood' flows to the top, ahead of his Aug. 8 birthday.

Just ahead of turning 20, Shawn Mendes continues his historic teenage years, as "In My Blood" rises 2-1 on Billboard's Adult Pop Songs radio airplay chart (dated Aug. 4). Already the only artist with three No. 1s before age 20 on the survey (which launched in the pages of Billboard in 1996), Mendes extends his mark with this fourth leader.    

The pop singer-songwriter previously ruled Adult Pop Songs with his debut entry "Stitches," which led the Feb. 6, 2016-dated chart; "Treat You Better," which spent six weeks at No. 1 beginning in October 2016; and "There's Nothing Holdin' Me Back," which began a five-week command on Sept. 9, 2017.   

Mendes, who turns 20 on Aug. 8, boasts twice as many No. 1s as a teen as each of the two runners-up for the honor: Avril Lavigne ("Complicated," 2002; "I'm With You," 2003) and Lorde ("Royals," 2013; "Team," 2014).

The Adult Pop Songs chart measures total weekly plays, as tabulated by Nielsen Music, among its reporting panel of 87 adult top 40 stations.