Justin Timberlake Honors Idol Garth Brooks With Impromptu Singalong

Getty Images

Justin Timberlake paid homage to one of his "idols" during the final leg of his 20/20 Experience World Tour -- and it wasn't Michael Jackson or Elvis Presley.

The 33-year-old singer went off-script at a concert earlier this month in Oklahoma City, honoring his "idol" and country star Garth Brooks with an impressive cover of Brooks' 1990 hit song "Friends in Low Places" one day after meeting the man himself in St. Louis.

PIC: Justin Timberlake Shares First-Ever Photo With Jessica Biel!

Timberlake even posted an Instagram pic on Dec. 4 after attending Brooks' concert, looking as elated as ever! 

Timberlake didn't need much help revving the crowd up for the impromptu singalong.

WATCH: Jessica Biel Shows Off Her Dance Moves at a Justin Timberlake Concert

Just watch the video, posted to YouTube by a concertgoer, below to see what we mean.

As his 20/20 Experience World Tour nears its end, wrapping up with back-to-back Las Vegas dates on Jan. 1 and 2, rumors have been swirling that the the former 'NSYNCer and wife Jessica Biel are expecting a baby. Though the couple has yet to publicly address the pregnancy rumors, Timberlake did post the couple's first photo together on his Instagram in October while in New Zealand.