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Taylor Swift and Max Martin Hit #1 With "Bad Blood"

Taylor Swift's new No. 1 hit, "Bad Blood," is not only the singer's fourth chart-topper on the Billboard Hot 100 but also a landmark for producer Max Martin, who notches his 20th No. 1 on the same chart.

The Swedish impresario's other credits include Backstreet Boys, Britney Spears, *NSYNC and many others, and Swift tells us that when she decided to take a more pop-focused approach on her latest album, "1989," Martin was the obvious choice to be the set's executive producer.

"I basically said to Max, 'I want you to co-executive produce this album with me. I want there to be a small group of people who work on this album so we can really make sure we focus on making a sound that's very cohesive and very signature to this album," said Swift.

She also explained that "Max was kind enough to produce the vocals for even collaborators that I worked with where he wasn't involved in the collaboration, just so we would have...vocals that sounded very similar throughout the record, just so we didn't have anything breaking up the cohesive nature of the album."

"Bad Blood" is the fourth official single from "1989" and followed "Shake It Off" and "Blank Space" to No. 1. She resumes her 1989 World Tour on Saturday (May 30) in Detroit.