(CNN) -- The rumor blowing up Saturday was that Day 2 of the Coachella Valley Music & Arts Festival could feature a surprise appearance by electronica icons Daft Punk. According to the Twitterverse, it would probably take place during the set of headliners Phoenix.
But when the special guest finally materialized on the main stage, it wasn't Daft Punk, it was R. Kelly. Yes, that R. Kelly.
The controversial R&B legend's unexpected appearance prompted festival-goer Katy Perry to reference last year's popular Tupac appearance on Twitter: "Production value has really gone up at (Coachella), it felt like R. Kelly was really there! #rkellyhologram"
Taking the stage near the end of night, Kelly joined the headliners for a mashup of their "1901" and his "Ignition."
Kelly wasn't the only R&B artist to make a cameo at Coachella on Saturday. John Legend premiered his Benny Benassi-produced single "Dance the Pain Away" in the Sahara tent during the DJ's set, and Solange made a guest appearance during the performance of her friends the xx. Their special Coachella remix of their cover of Aaliyah's "Hot Like Fire" and Solange's "Locked in Closets" injected an upbeat energy into an otherwise moody set.
Other Saturday crowd-pleasers included the Violent Femmes, who had fans dancing and singing along to their 1983 hits "Blister in the Sun," "Kiss Off" and "Add It Up." Although the songs were released before most of the festival-goers were born, they were familiar because of their ubiquitous presence on Los Angeles radio station KROQ.
Another Day 2 favorite was 2 Chainz, the Georgia rapper best known for the tracks "I'm Different" and "Birthday Song." Coachella organizers obviously underestimated his rabid fan base, and instead of slotting him onto the main stage, they relegated him to a much smaller tent. Admirers spilled out the back and sides of the tent as puffy clouds of smoke rose from the crowd.
Moby made his first appearance at Coachella since 1999, the festival's debut year. Even though he's branched out as a musician in recent years, he returned to his DJ roots, playing the dance tent accompanied by visuals of outer space -- courtesy of his friends at NASA.
"When I was growing up, I was obsessed with science fiction," he said. "And then I became obsessed with space and science, but I was a college dropout, so I was never smart enough to be a scientist. As a musician, I've made friends with people at NASA, so every couple of years, I find myself doing something with them. This is my hometown festival in some ways, and I only get nervous performing when I know people in the audience."
On the flip side, Janelle Monae trotted out her retro soul revue. The singer/funktress was eager to kick off her debut.
"I've heard a lot about the festival. This is my first time, so I'm excited about giving -- and having -- an experience that will be unforgettable."
To close the festival Sunday night, the Red Hot Chili Peppers returned for their third time headlining Coachella.