Justin Timberlake helps fan propose to girlfriend during Louisville concert

Justin Timberlake helps a fan propose during a concert in Louisville, Ky., on Sunday night.

Justin Timberlake isn't just bringing sexy back — he's helping rekindle good old-fashioned romance, too.

After crooning his song, "That Girl," the pop star abruptly stopped his Louisville, Ky., concert Sunday night to help one fan on stage to propose to his girlfriend.

"Josh called earlier, he's got something he wants to tell you," Timberlake said as he escorted Joshua Clemons and Kim Martin on stage.

Timberlake tells Kim Martin that her boyfriend, Joshua Clemons, has something to ask her.

Then amid the deafening squeals of the crowd, KFC Yum! Center crowd, Clemons made his pitch and got down on one knee.

Leading the applause was Timberlake himself, who later posted video of the proposal on YouTube.

"I was just like, 'There's no way, there's no way this is happening,'" Martin later told Louisville's WDRB TV.

Clemons takes over from opening act Timberlake.

To make the spontaneous moment happen, it took Clemons almost 100 emails and phone calls to reach Timberlake's manager.

"Friday, we finally caught each other on the phone then they told me Justin has a big plan and wanted to know if I was ready to do it big and I said, 'Definitely,'" Clemons told WDRB.

‘I was very surprised he took initiative to help us so much,’ Martin later told Louisville’s WDRB TV.

After the concert, Timberlake invited the newly engaged couple and Clemons' young daughter Mia backstage and supplied them all with autographs.

"I was very surprised he took initiative to help us so much," gushed Martin.

Timberlake was still basking in the honeymoon phase of his concert Monday when he tweeted out the video.

"And then this happened in Louisville ..." the "Suit & Tie" singer tweeted.