Coldplay: Kelly Jones and choir join band in Cardiff gig
A member of Bridgend Male Voice Choir said it was "mindboggling" to join Coldplay on stage to perform the Welsh national anthem.
The choir sang Hen Wlad Fy Nhadau towards the end of Tuesday's show at the Principality Stadium in Cardiff.
Meanwhile, singer-songwriter Hana Lili said it was "such an honour" to be a support act for the band.
Fans were also treated to a guest appearance from Stereophonics frontman Kelly Jones.
Speaking to BBC Radio Wales Breakfast, Chris Jones, one of the choir's performers said: "We walked on and I couldn't stop grinning.
"I looked around at the 80,000 people and I couldn't stop laughing to myself and thinking 'what the heck am I doing here'."
Mr Jones said Chris Martin, the lead vocalist and guitarist of Coldplay, spoke Welsh several times on stage.
"He made the effort and he was wonderful."
Mr Jones said one of the chorister's sons went to university with Martin.
He said: "They've kept in touch of the years, and he's always said 'if I do need a male voice choir I'll give Bridgend a ring'.
"He kept his word," said Mr Jones.
Kelly Jones of Welsh rockers Stereophonics was also a surprise performer at the show, playing the band's number one hit Dakota for the Cardiff crowd.
Hana Lili, from Sully, Vale of Glamorgan, was the first support act of the night, and told : "It was so surreal, I still don't think it's quite sunk in yet.
"Sometimes I just catch myself and think 'that was absolutely insane'."
She said she almost did not reply to the email asking her to perform.
"I got an email from Coldplay's live team asking me if I wanted to support them in Cardiff," she said. "At first my dad thought it was fake and told me to ignore it, saying it was one of those scams.
"I said I'll answer just in case, and I'm glad I did."
"I think it so brilliant that their ethos as a band is wherever they're going to they have a local support act."
Travel warnings
Commuters have been urged to plan their journeys ahead of the shows, with the M4 and surrounding roads expected to be very busy.
Coldplay were originally set to play a single night at the Principality Stadium, but a second night was added after overwhelming demand.
There will be a full city centre road closure from 16:00 BST to midnight on Wednesday.
Cardiff council said congested roads can be avoided by using its Park & Ride facility at the Cardiff City Stadium in Leckwith or the Park & Walk facility at County Hall, in Cardiff Bay.
Transport for Wales and Great Western Railway are both running extra services after the concert.