UPDATED: The studio behind ABC’s bubble drama series Nashville is looking to boost the show’s renewal chances by bringing in new showrunners. Thirtysomething creators Edward Zwick and Marshall Herskovitz will take the helm of the country music-themed series if it goes to Season 5, replacing current showrunner Dee Johnson, who will exit at the end of the current fourth season.

The showrunner assignment for veterans Herskovitz and Zwick, first reported by TVLine, falls under the first-look deal the duo inked last fall with Lionsgate TV, which co-produces Nashville with ABC Studios. It follows the decision by Johnson to leave the series at the end of Season 4.

NashvilleNashville has been an important series for Lionsgate TV, the biggest broadcast show for the cable and streaming-centric indie studio. The renewal of the modestly rated drama had gone down to the wire the last couple of seasons, mostly coming down to ABC and Lionsgate haggling over the big price tag of the show starring Connie Britton and Hayden Panettiere and eventually coming to an agreement. The showrunner hire is a pre-emptive move often employed by studios behind bubble series in an attempt to secure a renewal. For Nashville, the stakes are higher than usual this year as one of its biggest supporters at ABC, Paul Lee, recently exited in an executive shakeup. Nashville and Castle were the two established ABC drama series that did not get an early pickup earlier this month. (Castle‘s renewal is complicated by the need for new contract with star Nathan Fillion.)

Nashville‘s Live+same day ratings have been very low – it recently returned from hiatus to a 4.3 million total viewers and a o.9 adults 18-49 rating — and that was actually up from the winter finale. On the plus side, it has been a solid DVR gainer, and it has spawned a music and touring business. Creatively, Nashville faced a major challenge this season as it had to accommodate the extensive medical leave of one of its stars, Panettiere.

Johnson has been on Nashville since the first season, working alongside creator Callie Khouri.

“Dee Johnson is a creative powerhouse who has partnered with us on two iconic series, Nashville and Boss, displaying a singular commitment to creative excellence, open collaboration and superlative production oversight on both series,” said Kevin Beggs, Chairman, Lionsgate’s Television Group. “Without her we would not be in the privileged position of heading toward a fifth season of Nashville.  We consider ourselves lucky to have had her talents under our studio auspices over the last six years and look forward to many more collaborations together.”

Zwick and Herskovitz, who also exec produced My So-Called Life, Relativity, Once And Again and the influential online series quarterlife, previously had an overall deal at 20th Century Fox TV.

Through their Bedford Falls banner, Herskovitz and Zwick produced such movies as Legends Of The Fall, The Last Samurai and Blood Diamond, all of which were directed by Zwick, as well as I Am Sam and Traffic. Zwick most recently directed and produced Pawn Sacrifice starring Tobey Maguire and Liev Schreiber, which was released in September.