LONDON — When Taylor Swift began strumming "Everything Has Changed" on her guitar for the surprise set, the audience collectively gasped. Would Ed Sheeran, the other singer on the "Red (Taylor's Version)" track, make an appearance at Thursday night's Wembley Stadium show?

Whispers traveled throughout the 92,000 fans like the electricity surging through the glow-up wrist bands. As the lights illuminated bright red, fellow Swifties surmised the possibility. "Is Ed here?" many in the upper ring questioned.

After the first chorus, Swift paused her singing to say, "You guys were really singing that one loudly." A verbal interruption in the surprise set is a dead giveaway that something is up the singer's sleeve... or rather sleeveless blue dress.

"But I just feel like I'm not really doing it justice," Swift said and the decibel level in the stadium skyrocketed, because fans knew Sheeran was there. "Do you know what I mean? Something is definitely missing, and I'm trying to figure out what it is."

One of the diamond floor risers opened up to reveal Swift's best friend and fellow pop star.

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"I just feel so lonely, do you know what I mean? So it's a good thing Ed Sheeran is here," she said. Sheeran held the guitar strapped across his shoulder with one hand and waved with the other as he walked down the catwalk to meet the Eras Tour star at the end.

The audience sang along as Swift and Sheeran harmonized on "Everything Has Changed." The echoes of the chorus spilled out through the open roof and into the lukewarm summer night.

"That's what was missing, right Wembley?" Swift said smiling. "Everybody say hi to Ed Sheeran."

No introduction was needed for this crowd; Sheeran's reputation precedes him. He burst into another duet, "End Game" from "Reputation."

The light-up wristbands switched to bright green and fans thought the double mashup duet was a perfect gift. They absentmindedly expected "End Game" to be the final song until Sheeran dove into his love song "Thinking Out Loud."

One girl in section 548, row 18 began crying. "I love this song," she wept as mascara dripped down her cheeks.

At the end, the two best mates hugged and Swift ruffled Sheeran's bright red locks.

"This is one of my best friends in the world to the point where I feel like he's a second brother," Swift said with her arm slung over his shoulder. "We toured together on the Red tour and every time I am doing the 'Red' part of this show, I think about the memories we made. And now he is someone who plays Wembley like every week. This is regular for him and he works so hard and he's on tour right now and he's probably so tired, but he wanted to come play for you and do this for all of us."

Swift bowed down to Sheeran as he made his way back to the platform he entered on and she sat down at the piano to deliver a sweet mashup on the piano between “King of My Heart” from “Reputation” and “The Alchemy” from “The Tortured Poets Department.”

Where’s the trophy? That was an epic surprise set!

For a complete list of every surprise song and mashup, click here.

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