Katy Perry paid tribute to the victims of the Manchester Arena terror attack during an intimate London concert on Thursday (25May17).

The Roar singer shared a livestream video, titled Round 2, via Twitter ahead of the show, so her fans could have "the best seat in the house" for the gig, during which she performed her new tracks Chained to the Rhythm and Bon Appetit and older hits including I Kissed a Girl in front of a small audience of 90 people at the Water Rats venue.

The evening took a somber turn when Perry stopped to acknowledge the victims of the bomb blast in Manchester, which occurred as fans exited an Ariana Grande concert on Monday (22May17).

The London show was Perry's first since the terrorist explosion claimed the lives of 22 people and she tearfully addressed the tragedy.

"It's awful. It's awful," she tearfully told attendees. "Whatever you can do to help, you should... and if you can't do anything that's fine. But what you should do is not let them (terrorists) win."

She then asked for a moment of silence before resuming the show.

Hours prior to the performance, Perry retweeted a photo of Queen Elizabeth II visiting one of the surviving victims of the blast at the Royal Manchester Children's Hospital with the caption: "God bless The Queen and her kind heart #StayStrongManchester.”

It's not clear why she chose to perform the low-key gig at such an intimate setting, but she recently offered to play at the Water Rats to celebrate pal Roman Kemp's new London radio show. She phoned in to his Capital London Breakfast Show on 2 May (17) with a special message for the host.

She said, "You know, I'm going to be coming to the U.K., actually quite a lot coming up... Let's go to the pub, let's knock some down, and I'm going to suggest we go to Water Rats... I'm going to go to The Water Rats, and I'm going to play a show and you're coming and I think some people that are listening are going to be coming if they want to come. And we're going to drink some beers and we're going to sing some songs!"