The Script were joined by surprise guest Labrinth as they performed at Radio 1’s Big Weekend in Londonderry.
He joined the Irish band on their number one single Hall Of Fame, singing the part recorded by will.i.am.
Frontman Danny O’Donoghue said: “The crowd were absolutely everything I thought they would be. They love live music. They love getting out on the streets and singing their hearts out.”
Earlier Olly Murs took to the Main Stage in Derry’s Ebrington Square.
His set included Troublemaker and Army Of Two.
US rapper Macklemore received one of the biggest receptions of the festival when he played the In New Music We Trust stage.
He performed Thrift Shop to massive cheers and ended his set with Can’t Hold Us, during which he stage dived.
Nineteen-year-old Jake Bugg also played the main stage.
“It was brilliant, it blew my mind,” he said. “Looking at the line-up I didn’t think people would be interested to see me. But they seemed to really appreciate. Blew me away.
“You see different pockets of the crowd and its funny when you think they are cheering for you but really it’s because they’ve just seen the camera,” he joked.
Earlier Little Mix and 30 Seconds To Mars played the Main Stage.
The former X Factor group’s set included a mash-up of girl band classics including Destiny’s Child Bootylicious and TLC’s No Scrubs.
Jesy Nelson from Little Mix said: “We were just loving it. It was our first proper festival we’ve ever done and we can say that was one of our favourite performances we’ve ever done.”
Bruno Mars is headlining tonight’s line-up.
BBC Sound of 2013 winners Haim opened the In New Music We Trust stage and were followed by We Are The Ocean. Wretch 32 has also performed.
30 Seconds To Mars flew in from America for the event and brought several members of the audience on stage with them.
Lead singer Jared Leto said: “We arrived yesterday from California and it’s really our first show in Europe in support of our brand new album. It was fun, it was exciting.”
Around 40,000 people have attended the event.
Police said there had only been a “small number” of arrests over the first two days. They advised those attending the festival not to drink too much alcohol.
Paramore, Vampire Weekend and Olly Murs are among the other acts due to perform.
Other acts to perform on the final day include Everything Everything and Disclosure.