"Tryna strike a chord and it's probably A-minor."

Kendrick Lamar's most famous lyric was heard around the world at last weekend's Super Bowl.

An estimated 127 million viewers saw the rapper flash a devious smile to the camera as he delivered the line - a withering takedown of bitter rival Drake.

Taken from Grammy-winning track Not Like Us, it refers to accusations that the Canadian star had relationships with underage women - something he's denied.

But as 70,000 fans inside Caesars Superdome in New Orleans belted it out with him, it felt like Kendrick's winning play in the pair's long-running beef.

It's been public, personal and petty, but Kendrick has implied that he's waging a much wider war.

Not just against Drake, but against what he represents.

"Drake is the face of the hip-hop scene as it is," says Margs, a London rapper who hosts rap battles on his channel Pen Game.

The Canadian is a huge commercial success - the most streamed artist of the 2010s, 143 million Instagram followers and a fixture on party playlists and nightclub set lists.

His style is melodic and accessible. He sings.

In other words, he's as much a pop star as he is a rapper. And where Drake goes, others follow.

"A lot of people see him as being responsible for the watering down of the product," says Margs.

"There's people that like the commercial side of music that just want to dance and enjoy themselves and it have no substance to it.

"And then there's the other side which is deep-rooted in the hip-hop culture."

It's a culture Kendrick wants to defend and celebrate.

Speaking before the Super Bowl show, he said the "grit" had gone from the genre.

"When people talk about rap, the conversations I'm hearing, they think it's just rapping, it's not an actual art form," he said.

Kendrick also took issue with rap being "minimised to a catchy song or verse", and said his feud with Drake actually came "more from a space of more people putting rap to the back".

"You didn't see that grit, you didn't see that bite any more. So I always took that into consideration with my music," he said.

Not everyone agrees that a more mainstream-friendly version of rap makes Drake less credible.

His one-time rival Common recently defended him against the "pop star" label - saying that "he's still an MC" even though his songs are popular.

Kendrick, though, is passionate about rap as an artform, and said the success of Not Like Us and being chosen as the first solo hip-hop artist to front the halftime show "meant everything".

"To represent it on this type of stage is just everything that I've worked for and everything I believe in for the culture, I live and die by it," he said.

Hip-hop, a genre which has been around for 50 years, has a long history of protest.

Margs says "a lot of that has been lost" when comparing current trends with the genre's origins.

"They cared about the message and what it stands for because hip-hop was something that was heavily politicised," he says.

"People used to use their voices in hip-hop to protest and get their messages out."

The political messaging in Kendrick's halftime show came from the start when actor Samuel L Jackson, dressed as US government icon Uncle Sam, introduced the rapper.

From there, it included references to the black power movement, imagery of a divided United States and, just before the finale, the line: "This is bigger than the music."

It's a time of political change in the US following the re-election of Donald Trump, who was at the Super Bowl.

"There's no better time for people to stand on business and talk about things that matter," Margs says.

Kendrick - and his beef with Drake - also hark back to the origins of hip-hop in another way.

He's said he sees rap as a sport - and battle raps were his inspiration for the back-and-forth with Drake.

These face-offs - as seen in the Eminem film 8Mile - are where artists compete live, swapping disses and trying to spit the best bars to take home the prize.

It's rap in its purest form - substance over style and a focus on lyricism.

Kendrick said it's always been that way for him, and it's a vital part of finding the "grit" and "bite" he feels is missing.

"I still watch battle raps, this has always been the core definition of who I am and it's been this way since day one," he said.

Margs thinks Kendrick's success will shine a light on battle rap, but he acknowledges emerging rappers are now finding new ways to cut their teeth.

Among them is Layyah, who was the first female rapper to win The Rap Game UK.

She's Team Kendrick, but doesn't plan on following his example on battle rap.

Layyah says rap artists she looks up to like Central Cee are "definitely not battle rappers" but have found success and respect through other routes.

"We have so many platforms," she says. "It's more like who can make a great song and then who can make the best routine to it.

Margs thinks that's "taken away from the art form a little bit".

"You can win a battle on social media just through popularity or being funny... whereas with battle rap it's all about your lyrics and your skill."

As for Kendrick's beef with Drake, it's stayed quiet since Not Like Us was released last summer.

Some people took the "Game Over" at the end of Kendrick's Super Bowl set as the end of the battle, and Drake's just released Gimme a Hug.

In that he suggests he wants to put the beef behind him and "get the party lit".