This is the transition from a groove in 'normal' time (with a back beat on 2 and 4) to the 'half time' feel with a single back beat on 3.
Remember that the tune DOES NOT slow down, it does feel as if the tune is slowing down but the tempo stays the same!
Remember that the tune DOES NOT slow down, it does feel as if the tune is slowing down but the tempo stays the same!