WATCH: Fallon, Joel Form 2-Man Doo-Wop Group on “Tonight Show”

The two performed "The Lion Sleeps Tonight" with the help of an iPhone app that loops vocals.

Billy Joel had "The Tonight Show" audience enthralled. The music legend sang a capella doo-wop with Jimmy Fallon and delivered his first performance on a late-night show in 14 years.

But before the music, Joel talked about his upcoming radio channel on Sirius that will air for three months. Joel said he will program music he listens to and talk about his road experiences. The "Uptown Girl" singer and the "Tonight" host also made plans to crash oldie-playing radio station WLMG in the Hamptons sometime this summer.

Talk then turned to Joel's Madison Square Garden residency. He's currently performing once a month for as many months as audiences demand.

Apparently, thanks to Fallon, one of those concerts got off to a late start. The late-night host had been singing doo-wop with his father and Joel backstage before a performance, but the trio got so carried away they ended up causing the concert to be delayed for 20 minutes.

"Your dad kept coming up with these good ones," Joel said.

With the crisis in the Ukraine, Fallon also brought up that Joel was the first American rock 'n roll act to play in Russia.

"We went there when they were the Soviet Union back in '87 and they had never seen a rock and roll show. They had had bands with a Polish PA system. We brought the same stuff we use at the garden," Joel explained, "lights, staging and a sound system. They were a little freaked out at first."

The 64-year-old said the experience made him let go of any initial reservations he had.

"The cold war kind of ended for us right there. I said 'that's it, I'm not going to fight with any of these people.' The crowd went crazy, I trashed the piano, they trashed the chairs," Joel said.

"With everything that's going on in the Ukraine, maybe we have to send you back," Fallon joked.

The pair then formed a two-man doo-wop group and performed "The Lion Sleeps Tonight" with the help of an iPhone app that loops vocals, before the two concluded Joel's appearance with a rendition of his classic "You May Be Right."

Watch the acapela performance above.

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