Harry Styles and Niall Horan performs at Staples Center on Dec. 4, 2015 in Los Angeles.

Harry Styles and Niall Horan performs at Staples Center on Dec. 4, 2015 in Los Angeles.

Kevin Winter/Getty Images for iHeartMedia

There’s a One Direction reunion of sorts on the Billboard + Twitter Top Tracks chart (dated May 20), as Harry Styles’ “Sweet Creature” and Niall Horan’s “Slow Hands” debut at Nos. 2 and 3, respectively. Stopping both of them from reaching the top is BTS’ “Not Today,” which returns to the top, vaulting 24-1 (more on that in a moment).

Billboard + Twitter Top Tracks is a weekly ranking of the most shared and/or mentioned songs on Twitter in the U.S., ranked by the volume of shares over a seven-day period (Monday to Sunday). The most recent tracking week ended on May 7.

Styles premiered “Creature” on May 2 alongside an interview with Zane Lowe on Apple’s Beats 1 radio service before its release to retailers and streaming services shortly after. The tune shot to No. 1 on the real-time Billboard + Twitter Trending 140 chart the same day.

“Creature” follows Styles’ debut solo single, “Sign of the Times” which entered at No. 1 on the Top Tracks chart and No. 4 on the Billboard Hot 100. Both “Times” and “Creature” feature on Styles’ self-titled debut album, which was released May 12.

The “Creature” buzz helps Styles pick up 892,000 Twitter mentions for the week ending May 7, according to Next Big Sound, a gain of 27 percent.

Just below, Horan’s “Hands,” enters at No. 3 after its release on May 4. The funk-pop tune follows his first solo single “This Town,” which was issued in October. “Town” soared to a No. 1 debut on Top Tracks, holding the rank for four weeks.

The new single prompts an 848 percent surge in Horan’s Twitter mentions to 1.1 million for the week, and rockets him 24-5 on the Social 50 chart. The top five showing is his best rank since an equal No. 5 rank on the chart for Dec. 31, 2016.

The two tunes are blocked from the summit by BTS’ “Not Today,” which surges 24-1 for a third nonconsecutive week atop the list. The song first topped the tally on the March 11-dated chart, and scored a second week at No. 1 on March 25. The tune returns to No. 1 on the latest tally following activity surrounding BTS’ nomination for the fan-voted Top Social Artist category at the Billboard Music Awards. (Fans can vote for the category via Twitter, using specific hashtags.)

Also in the top 10, Migos’ “11 Birds” flies in at No. 8, giving the group its fourth top 10 hit on the Top Tracks chart, following “Bad and Boujee,” featuring Lil Uzi Vert (No. 1 for one week), “Dab of Ranch” (No. 9) and “Slide” (No. 7), with Calvin Harris and Frank Ocean, all in 2017.

The rap trio released “Birds” and a Champs Sports-sponsored music video for the track on May 1 as a tribute to their hometown NFL team, the Atlanta Falcons, and specifically, the team’s wide receiver Julio Jones, who appears in the clip. The video has risen to more than 2.6 global views on YouTube through May 11.

Migos also earn a second debut on the latest chart, as “Slippery,” featuring fellow Atlanta rapper Gucci Mane, starts at No. 36. “Slippery” arrives after its music video premiere on May 7. The clip has raced to 7.8 million worldwide views through May 11. The track is on the group’s Culture album, which debuted at No. 1 on the Billboard 200 earlier this year.