Chris Young, Cassadee Pope Crown 
the Country Airplay Chart

Courtesy of Southwest
Southwest surprises guests onboard Tennessee One with a surprise performance by Chris Young and Cassadee Pope.

Chris Young and Cassadee Pope's duet "Think of You" rises 3-1 in its 18th week on Billboard's Country Airplay chart (dated May 14), increasing by 8 percent to 46.8 million audience impressions in the week ending May 1, according to Nielsen Music. The song is Young's seventh No. 1 and Pope's first.

"Think" -- from Young's fifth studio album, I'm Comin Over -- follows the title track as his second Country Airplay leader from the LP, which debuted at No. 1 on Top Country Albums (Dec. 5, 2015) with 57,000 sold, becoming his first leader on the list. It has sold 193,000 date.

Young co-wrote "Think" with Corey Crowder and Josh Hoge. "Cassadee was always my first pick to sing the duet with me," Young tells Billboard. "It's a big song, and I knew I needed someone with a powerful voice to match."

Pope, the 2012 third-season winner of NBC's The Voice (and the first woman to win the prize) rules Country Airplay in her fourth appearance on the chart. She previously peaked as high as No. 10 in 2014 with "Wasting All These Tears," her launch country single.

Chris Young and Cassadee Pope Perform 'Think of You' at 2016 ACM Awards

"Cassadee was such a standout on The Voice," says Big Machine Label Group chairman/CEO Scott Borchetta. "Every time she performed a country song, I would ring up Republic president Monte Lipman in New York and say, 'This girl Cassadee, I think she's country.' We didn't know for sure until the day after she won The Voice that she wanted to pursue her country influences."

Young is likewise a former TV competition champ, and his latest Country Airplay coronation syncs with the 10th anniversary of his winning Nashville Star (May 2, 2006). The next day, RCA Nashville announced that it had signed him.

Meanwhile, the country male/female duet is a classic sound for the genre (e.g., Dolly Parton and Porter Wagoner, Loretta Lynn and Conway Twitty), although not so common at No. 1 since Country Airplay began in 1990. "Think" is only the fifth duet between a solo male and female (with each artist sharing lead credit) to top the chart, following Keith Urban and Miranda Lambert's "We Were Us" (2013), Brad Paisley and Carrie Underwood's "Remind Me" (2011), Anita Cochran and Steve Wariner's "What If I Said" (1998) and Reba McEntire and Vince Gill's "The Heart Won't Lie" (1993).

10 SPOT: Two songs enter the Hot Country Songs top 10. Luke Bryan's "Huntin', Fishin' & Lovin' Every Day" rises 11-9, led by its 9-8 lift on Country Airplay (31.7 million, up 6 percent) and 16-9 dash on Country Streaming Songs (2 million, up 8 percent). The track is Bryan's 21st Hot -Country Songs top 10.

Dustin Lynch likewise reaches Hot Country Songs' top tier, with "Mind Reader" (Broken Bow), up 13-10. His fourth top 10 is driven most heavily by radio, as it climbs 6-4 on -Country Airplay (38.5 million, up 6 percent).

DIGGING IN: The highest debut on Country Airplay belongs to Florida Georgia Line, whose "H.O.L.Y." launches at No. 26 with 10.1 million impressions following its April 29 arrival. The song previews the duo's third full-length, Dig Your Roots, due this summer.

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'NEW' ALBUM: Josh Kelley's eighth studio set, New Lane Road, opens at No. 29 on Top Country Albums (2,000 sold). It's his first entry since 2011's No. 16-peaking Georgia Clay. Kelley is currently touring with his brother, Lady Antebellum's Charles Kelley, on the latter's solo The Driver Tour.

Speaking of Lady A, the group's Hillary Scott enters Hot Country Songs at No. 33 with "Thy Will" (billed as by Hillary Scott & The Scott Family). The track bows almost entirely due to sales, entering Country Digital Songs at No. 22 (11,000 sold). It also starts at Nos. 2 and 6 on Christian Digital Songs and Hot Christian Songs, respectively, and previews the forthcoming faith-based LP Love Remains.

This article first appeared in Billboard's Country Update -- sign up here.