In public procurement a temporal separation of award and actual contracting can frequently be observed. In this paper we give an explanation for this institutional setting. For incomplete procurement contracts we show that such a separation may increase efficiency. We show that efficiency can be increased by post-award, pre-contract negotiations between the award-winning seller and one of the 'losing' sellers. Surprisingly, the efficiency gains can be higher if the award is given to a seller with a lower reputation for quality instead of to a seller with higher reputation. Under certain conditions post-award, pre-contract rent-seeking activities also increase efficiency. This is always the case if the procurement agency is corrupt, but may also occur in the case of lobbying.