Thanks to big syncs by the Weeknd, Motley Crue and yacht rock icon Christopher Cross, season four of Netflix’s “Cobra Kai” raised the bar in more ways than just its viewership, which propelled the show to No. 1 on Netflix’s English series chart for the two weeks following its New Years Eve release. Extending the storylines introduced in the beloved 1980s film series “The Karate Kid” and featuring many of its original stars, the series continued to find effective musical tie-ins to drive the narratives around 50-somethings Daniel (Ralph Macchio) and Johnny (William Zabka) as they pursue yet another All Valley karate tournament victory for their dojos.

This time around, the familiar ‘80s metal and soft rock classics were complimented by deeper cuts from those genres, knowing references to cult-classic songs and artists and more contemporary fare simpatico with the daily lives of its many teenage characters. Season four also sported a guest appearance by Carrie Underwood, who went from gushing about “Cobra Kai” on Twitter to recording an iconic track from “Karate Kid” lore (it can be found on the recently released “Cobra Kai Season 4, Vol. 1 & 2” original soundtracks, featuring score by series composers Leo Birenberg and Zach Robinson).

Variety connected with “Cobra Kai” co-writers and executive producers Josh Heald and Jon Hurwitz, as well as music supervisor Michelle Johnson, to discuss the musical highlights of season four and what’s in store for the highly anticipated season five later this year.

How has the music evolved on “Cobra Kai” since season one?

Michelle Johnson: I’ve been a fan of the show since season one, when it was on YouTube. There were the big hits placed in the show that felt so satisfying and right, and every season you got a little bit more. What I feel like hadn’t been dug into was some of the more background songs — trying to expand our genres a little bit. That’s a holistic approach I’ve been trying to do from top to bottom — even with the background stuff, making them as fun and energetic as the big moments from the well-known songs. Some of my favorite placements are deep background songs or party songs. The party at Stingray’s house had some fun stuff, like Quixotic Sound’s ‘You Make Me Wanna,’ when the couples started fighting. It’s Stingray’s house, where he’s hanging out with teenage kids. It can’t be Metallica all night. It had to be a little bit more youthful.

For the first time, you had a major current pop song sync with the Weeknd’s “In Your Eyes.” Tell us more about that high school prom scene, where the Miguel and Sam characters are jealously watching the Robby and Tory characters dance together.

Jon Hurwitz: We’ve had some moments where we’ve had current music on the show when we’re with the kids, but it is rare to have something that’s a bigger song. This was the prom — we wanted it to make a splash. We wanted it to feel the way a prom would, which would involve songs that you’ve probably heard before. It played a role in story as well. This was a big moment between two of our lead characters dancing, and for the other leads to be watching them and and getting uncomfortable. So it needed to have that high production value that the feel of that moment has. It’s a big moment on the show and it felt appropriate to have a modern song.

Johnson: I knew the Robby-Tory dance would be the featured moment and that’s what would be on camera, so I pulled together a small list of selects from current pop that the guys might not necessarily know. There’s something about that Weeknd track that has a foot in the ‘80s, so I thought it would feel at home in the show. We built that episode around that song.

Music plays a key role for both Johnny and Daniel’s characters, but they seem to be frozen in time — Johnny is perpetually stuck in ‘80s hard rock and Daniel still listens to Christopher Cross.

Josh Heald: When you look at that first “Karate Kid” movie, Daniel and Johnny had very different sounds. Daniel had this Bill Conti, almost Vivaldi-like orchestral, sweeping strings and horns and everything else, whereas Johnny and the guys had this very energetic, electric guitar sound of aggression. We kind of drew a through line to who Johnny was then. That’s the music in his head. That’s how he related to his friends. They kicked some ass and they listened to Metallica and it made sense that for a guy like Johnny, he would still kind of rely upon that music now. For Daniel, that was a more uplifting time — a time where, not that there wasn’t a care in the world, but he came through that period unscathed. So there’s an optimism to his music that’s less aggressive and more relaxing. It has that Peter Cetera, Christopher Cross kind of vibe.

There’s a great moment where Daniel sings “Sailing” in the car with Miguel, who has no idea what he’s hearing. My understanding is that Christopher Cross songs can be difficult to license for fear that they’ll be used to make fun of yacht rock.

Heald: The song did come with some caveats — we weren’t allowed to do anything where we were actually on a boat sailing. We live in an interesting time where artists have to be protective of their material so they’re not signing up for mockery. We’re mindful of that as well. We don’t want to use a song to make fun of it. We actually celebrate yacht rock. We love the the yin and yang of Johnny’s aggressive hard rock and then Daniel truly, earnestly celebrating a different type of what rock music can be.

Johnson: This is totally Daniel’s jam, right? He loves this song and it’s also a great moment bonding with Miguel.

Have there been any other songs you were dying to use but just couldn’t license for one reason or another?

Hurwitz: At the end of season two with the school fight, “Welcome to the Jungle” by Guns N’ Roses was going to be in there, and it worked great. It didn’t obviously last through the whole fight, but it was also expensive and we couldn’t afford it. We thought, how are we gonna not have that?

Heald: We were, like, selling furniture to get it. We were dug in, and then Zach and Leo said, we want to write something here and you don’t have to use it, but we want to write it. They love a challenge. They love trying to write their way into us not choosing a nostalgic song, and it becomes a fun exercise. Usually, they win. The moment we heard what they came up with for the fight scene, there was no turning back.

Twisted Sister’s Dee Snider made a cameo in season three, and now you have Carrie Underwood singing Survivor’s “The Moment of Truth” from the original “Karate Kid” soundtrack, as a way to introduce the All Valley karate tournament. How did she get involved?

Hurwitz: This was born less out of, “Hey, let’s put Carrie Underwood on the show,” and more out of our love as a group for the All Valley board. Those characters are the most relatable to us because like us, they’re trying to put on an awesome tournament. When we’re in their world, we can imagine a board member talking about having some celebrity appearance there. In terms of Carrie Underwood herself, when the prior seasons came out on Netflix, we were starting to see celebrity fans enjoying the show and tweeting about it, and she was one of them. It was always in the back of our minds. We thought, wouldn’t it be hilarious when they’re talking about the Malcolm Jamal Warner incident in episode six, and Ron comes through with a giant star? Her voice is perfect for that cover. We reached out and quickly were told that she was into it.

Heald: We’ve been fortunate that we have a hit on our hands here, because it’s easier to start a conversation with somebody when you’re not telling them go to this website you’ve never heard of and do these nine steps and multiple hoops to hop through to see our show. There are a couple of guys from two Rock and Roll Hall of Fame bands who would love to come play with us and we’d love to play with them. Because of COVID and everything else, we haven’t been able to pull it off yet, but we’ll see. We don’t want to feel gratuitous, like, hey, enter from stage left, this person! We don’t want to plagiarize ourselves.

There are also some deep musical references in season four, like the ‘80s thrash metal band Exodus being compared to “shitty Metallica” during an argument between two characters, and the Def Leppard instrumental “Switch 625” in the final scene of the last episode.

Heald: I’m gonna give Michael Jonathan Smith credit for the Exodus line. If it wasn’t him, I apologize to our writers room, because there’s a lot of cooks in the kitchen. That was in a very early draft of that scene. We had so much fun with it because it’s so comedic. We all wanted to get our fingers dirty on it and it ended up being a collaboration between the original writer, the writers room and those two performers.

Johnson: I’m a huge Def Leppard fan, and I’d been pitching them all season, but never that song, I guess because it was an instrumental. I figured they’d want a vocal song there, so I never considered it. I was pitching a bunch of ideas for that scene, and our editor Zack Arnold got back to me and said, these are all great, but there’s a thing we’ve been wanting to do, and we’re going to do it, so let’s see if we can make it happen. It’s perfect there. I was also very excited to get Judas Priest in the show and for the Gary Clark Jr. song, ‘Gotta Get Into Something,’ that Kenny dances to before school. That was super fun, and a little bit maybe out of the wheelhouse of the music in the show, but it fit so great.

What if anything can you reveal about season five? Will it be out in 2022?

Johnson: I think we’re stepping up the music even more with this next season. I’m not going to name the song, but if it sticks, I’m going to be incredibly happy, because it was something we tried in season four but couldn’t make happen.

Heald: There’s a great assumption and expectation that season five will be released in 2022. We don’t have a release date yet, so I can’t speak from a position of authority, but I have every reason to believe and expect, based on the drum beat of where we are, that it will come out this year. We finished production. We’re in post-production, so we are just now starting to have a lot of the conversations about licensing and making choices. Can we get this song? What are the options for a song that sounds like this? I could say right away just from what we’ve been in post with so far, there are some huge songs that are iconic and new sounds for characters that we haven’t heard before, new sounds for new relationships that haven’t been explored before and more of what you love.