In my humble opinion, Marichyasana D (as demonstrated by Sharath Jois in this video) is one of the hardest poses in the Ashtanga Yoga Primary Series.

Great clip of Sharath in the shala in Mysore-amazing how he is able to stay really focused whilst his son plays around a few feet away from him. I also thought it interesting how high he stays on his toes when he jumps back & rolls forward-thoughts on that anyone? Thank you to  Madeleine Warwick  for sharing