Two of the more athletic fighters in the UFC roster in Francis Ngannou and Uriah Hall were training together at Xtreme Couture in Las Vegas. Unfortunately they’re also two weight classes and several pounds apart, so when they sparred together, Hall described it as “one of the scariest moments” of his life.

Watch the clip below with Ngannou and Hall having a fun session together ahead of their bouts this January.

Ngannou will face Stipe Miocic for the UFC Heavyweight title on January 20, 2018 at UFC 220. Hall, on the other hand, will face Vitor Belfort a week earlier at UFC Fight Night: Stephens vs Choi.