I've lost sprints in every possible way and then some. But that reminds me of a ride when 3 or 4 of us watched each other for too long and the sprint was won by the only guy on a slick tire MTB who creeped in from behind - we never thought he would contest the sprint. But he was so exhausted afterwards that he barely could hang on at the back for the remaining 40 km. We dropped him repeatedly, but waited for him every time.