Khalid faced the Sassanids with about 5,000 cavalry and 10,000 infantry. Cavalry were divided into two equal divisions and deployed at the flanks. The strategy of the Persian commander in chief, Andarzaghar, was to go on the defensive and let the Muslims charge first. He planned to hold off their attacks until they were worn out, then launch a counter-attack to rout the weary Muslim army. The first phase of the battle went according to Andarzaghar's plan. Khalid ordered a general attack. The Sassanid army had reserves which they employed to replace their men in the front line, giving them the upper hand over the Muslim army and helping them to carry out their scheme to wear out their opponents. During this time, Khalid is said to have duelled with a Persian champion of gigantic proportions known as "Hazar Mard" (A Thousand Men) and killed him, which was a psychological victory for the Muslims.