With the onset of winter, Mithridates sought to take advantage of a Roman feint against one of his outposts. He sent his sick, his wounded, and his cavalry east into Bithynia. The army included Pontic phalangites, Pontic legionnaires, Thracian and Galatian mercenaries, and the cavalry. The Pontic column was commanded by Neoptolemus, who was the brother of Archelaus. In the middle of a snowstorm, Lucullus met these forces with ten cohorts along the banks of the Rhyndacus. The Romans had a small advance guard of auxiliaries and cavalry on the opposite bank of the river. The combined Roman forces attacked. The Pontic forces turned to defend themselves. The battle was hard, and the Mitridatic forces fought bravely, but they could not withstand the pressure of the Roman attack. Plutarch and Appian record 15,000 men and 6,000 horses as being captured during the battle.
Subsequently, Mithridates completely abandoned his position, sailing north while his army marched overland. Lucullus again routed them at the confluence of the Aesepus and Granicus Rivers.