Britney Spears Reacts to 'Hold Me Closer' Collab with Elton John Reaching No. 1

getty (2) Britney Spears and Elton John

Britney Spears had "the best day ever" thanks to the success of her new song with Elton John.

On Friday, Spears, 40, and John, 75, released their collaboration "Hold Me Closer," which was an instant hit as it reached No. 1 on iTunes in the U.S. and dozens of other countries, Spears said.

She reacted to the song's success with an impromptu video on Twitter, addressing John in her best British accent.

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"Hello Sir Elton John we are like No. 1 in 40 countries," she says before yelling: "Holy s—! I'm in the tub right now and I'm about to go have the best day ever and I hope you're well."

John responded to Spears' video: "Hey Britney!! Thank you for this message. You've made my day!! Hope everyone has the best day dancing to our song! #HoldMeCloser."

He also reacted to the song's popularity himself, tweeting alongside a clip of the song. "I'm thrilled with the response to #HoldMeCloser I wanted to do a fun, happy summer track so was ecstatic when @britneyspears agreed to be a part of it! She truly is an icon, one of the all-time great pop stars & I love her dearly. I hope you all love it!" John wrote.

The beloved duet marks Spears' first release since her 13-year conservatorship ended in November.

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"Hold Me Closer" combines the chorus of John's 1972 smash "Tiny Dancer" and verses of his 1992 hit single "The One" with a fresh, dance-pop production.

On Sunday, Spears wrote on Twitter, "Complacency has always been a boring tactic that feels safe … music ... creation ... producing is where my heart lies and lifts me with inspiration !!! I've had the opportunity to work with someone who is beautiful and kind on all levels …"

She added, "I'm honored and I feel loved by his awareness and acknowledgment, not by only my involvement with a song but by my struggles and what I've been through !!! He knows the hardships of the world on a bigger scale ..."

"You can lose your individuality on a fake tale of how other people may perceive you and some idiots like me fall into the trap cause unfortunately I do care … but at the end of the day …"

In an interview with The Guardian, John opened up about how he helped Spears make her highly anticipated return.

He said that when producer Andrew Watt initially finished the song's remix, they were unsure about who could join him on the track. That's when John's husband David Furnish suggested Spears serve as a feature.

RELATED VIDEO: Britney Spears Makes Her Official Return to Music with Throwback Elton John Duet 'Hold Me Closer'

"He said it would be wonderful for Britney Spears to do it," John told the outlet. "I said, that's a pretty amazing idea. She hadn't done anything for so long. I'd been following what's been happening to her for a long time."

Though Spears agreed to join the track, she couldn't go to London to record it because she was on her honeymoon with husband Sam Asghari. So instead, the "Toxic" singer recorded at Watt's studio in Los Angeles – finishing the vocals in less than two hours, per The Guardian.

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"She sang fantastically," John said. "Everyone was saying they don't think she can sing anymore. But I said, she was brilliant when she started so I think she can. And she did it, and I was so thrilled with what she did."

He added: "We had to get her to approve what she did. She's been away so long – there's a lot of fear there because she's been betrayed so many times and she hasn't really been in the public eye officially for so long. We've been holding her hand through the whole process, reassuring her that everything's gonna be alright."