He was no stranger to a heart-wrenching ballad.
Elvis Presley was the undisputed King of Rock 'n' Roll, there's absolutely no doubt about that.
But when he refrained from swinging his hips and shaking his signature "rubber legs", he was capable of breaking hearts at a less frantic tempo.
Presley's deep, rich crooning voice was tailor-made for singing swooning ballads and melancholic love songs.
Throughout his career, he took on a number of sad songs, some of which felt as though they were written for him specifically.
Elvis didn't write his own material and was reliant on other songwriters' words, so he often picked songs that meant something to him.
One of his favourite artists of all time was Hank Williams, often singing his songs in intimate, casual settings in front of his nearest and dearest.
There was one particular song of Williams which Elvis called "the saddest song I ever heard", before he covered it during what is now considered an iconic performance.
In 1949, pioneering American singer-songwriter released the song 'I'm So Lonesome I Could Cry' as a B-side to 'My Bucket's Got A Hole In It'.
Now a country music standard, it contained all the hallmarks of what made the genre's ballads so impactful.
Williams wrote the song about his tumultuous relationship with his first wife, Audrey. Going by his lyrics, it seemed like the singer was in a continued state of crippling desperation.
The state of his crumbling relationship with Audrey can be chronicled throughout Williams' entire discography as an artist.
“Did you ever see a robin weep / When leaves begin to die? / Like me, he’s lost the will to live /I’m so lonesome, I could cry," are now iconic mournful lyrics.
Hank Williams died before Elvis even released his first single, but his music and lyrics influenced Presley immeasurably.
Almost instantly after performing it on his syndicated radio show that year, 'I’m So Lonesome I Could Cry' became a fan favourite and a staple of the musician's setlist.
Listening at home was a young Elvis, who felt an attachment to the song's sadness, and found himself a hero in Hank.
Williams passed away on 1st January 1953, over a year before Elvis would released his debut single.
But 20 years later, Presley would cover 'I’m So Lonesome I Could Cry' during an incredibly special performance - his 1973 show Aloha from Hawaii.
Before performing the song to the world, he said: "I’d like to sing a song that’s probably the saddest song I ever heard."
Williams originally wrote 'I’m So Lonesome I Could Cry' as a spoken-word piece, and to record it as his alter-ego "Luke The Drifter".
Feeling it was far too genteel to record, he was convinced otherwise by his friends and fellow musicians.
Thankfully, he did, so Elvis could hear it and reimagine the song in his own imitable style.
He's not the only artist to cover the ballad, of course, given its enduring popularity among newer generations of artists.
Johnny Cash covered it in 1960, revisiting the song with Nick Cave in 2002. The Everly Brothers and B.J. and the Triumphs also covered it, the latter scoring a No.8 on the US
It's a testament to Hank Williams' timeless songwriting, one that details the complexity of love and the desperation of falling out of it.
The Hank Williams and Elvis Presley connection doesn't end with 'I’m So Lonesome I Could Cry', however.
Presley's manager, Colonel Tom Parker, was also fond of Williams, and wanted to make a film of his life with Elvis in the leading role.
Approaching producer Sam Katzman about making the movie with MGM, he said he'd promote the film even if Elvis didn't win the role, which he didn't in the end.
By the time the film was being made, Elvis was a cultural phenomenon. Williams' first wife Audrey felt his casting would turn the film's production and release into a circus.
Your Cheatin' Heart eventually came out in 1964, with George Hamilton securing the role of Hank Williams.