The buyer of a homogeneous input divides his input requirements into two contracts that are awarded to different suppliers. He uses a sequential second-price auction to award a primary and a secondary contract. With a fixed number of suppliers the buyer pays a higher expected price than with a sole-source auction. The premium paid to the winner of the secondary contract must also be paid to the winner of the primary contract as an opportunity cost. When entry is endogenous, we identify the conditions under which a secondary contract can increase the number of suppliers and lower the expected price.