The BBC Radio 2 DJ has revealed the 'Hello' hitmaker was ''really scared'' about her performance on the Pyramid Stage at the Worthy Farm festival, and even broke down in tears during their chat before the set.
Jo told The Sun newspaper's Bizarre column: ''She was really scared, really, really scared. We were doing the interview and at one point she had to stop as she was in tears.
''She was saying how much Glastonbury meant to her, and she'd been going since she was a child.
''She was just so stricken with nerves, absolutely panic stricken.''
However, Adele - who has spoken about her battle with stage nerves in the past - soon connected with the massive crowd when she got on stage.
Jo said: ''It was amazing to see somebody like that, then to witness her walking out on stage, and doing the most incredible set and see the confidence oozing out.
''She had this connection with all these people, and to know that half an hour before she'd been in tears at the thought of walking out there.''
In June 2017, Adele performed in front of a record-breaking crowd of 98,000 at Wembley Stadium, but revealed in a handwritten note buried inside her programme that she was considering quitting touring.
She said: ''So this is it after 15 months on the road and 18 months of 25, we are at the end.
''Touring is a peculiar thing, it doesn't suit me particularly well. I'm a real homebody and I get so much joy in the small things. Plus, I'm dramatic and have a terrible history of touring. Until now that is!
''I've done 119 shows and these last four will take me up to 123, it has been hard but an absolute thrill and pleasure.
''I only ever did this tour for you and to hopefully have an impact on you the way that some of my favourite artists have had on me live.
''And I wanted my final shows to be in London because I don't know if I'll ever tour again and so I want my last time to be at home.''
Although she hinted at quitting touring, Adele is known to be working on a comeback album, which will mark her first since 2015's '25'.
Meanwhile, in the place of Glastonbury this year, which was postponed until 2021 due to the coronavirus pandemic, the BBC is set to air 'The Glastonbury Experience', to mark Glastonbury's 50th anniversary.
Music-lovers will be able to watch iconic sets from the past five decades, including Adele's, on BBC Two, BBC Four, BBC iPlayer and radio this weekend.
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