Full tilt Pronghorn

I was shooting a male pronghorn in the Little America region of Yellowstone as it beat up a sage bush, when it turned to look back and started huffing and puffing.  Following it's gaze, I saw this second male racing across grassland.  As I followed the newcomer trying for some action shots, the first male took off, running hard.  Both of them went over a hill so I couldn't get any shots of both in motion.  I did get lucky and get some good views of the first runner in motion.  Here he is with his legs gathered under.  (7D2, 100-400 f4 IS II, 1/1600s, f/10, iso 800, tripod with head somewhat loose)