0639 GMT - U.S. Treasury yields and eurozone government bond yields fall in European opening trade as oil prices decline on the prospect of a deal between the U.S. and Iran. "Markets continue to err on the side of new momentum for diplomacy between the U.S. and Iran on breaking the energy-choking deadlock," analysts at KBC Bank said in a note. Investors await key input from flash estimate purchasing managers data for September. The 10-year U.S. Treasury yield falls 2.2 basis points to 4.944%, while the 10-year German Bund yield declines 1.3 basis pionts to 3.436%, according to Tradeweb.