Ivan Alexander had troops of 8,000 while the
Byzantines were only 3,000. There were negotiations between the two rulers but the Bulgarian emperor deliberately prolonged them because he was awaiting reinforcements. In the night of July 17 they finally arrived in his camp (3,000
cavalrymen) and he decided to attack the Byzantines the next day.
Andronikos III Palaiologos had no choice but to accept the fight. The Byzantine army consisted of 16 squads and six of them made up the first column. The right wing was commanded by the
protostrator, the left wing was under the
megas papias Alexios Tzamplakon, and the center was commanded personally by the emperor. Together with the emperor were his most trusted nobles
John Kantakuzin and Manuel Komnenos Raoul Asen, brother of
Irene Asanina.The army formed a wide front in two lines with the flanks positioned behind the center forming a crescent. The battle began at six in the morning and continued for three hours. The Byzantines tried to prevent the Bulgarian cavalry from surrounding them, but their manoeuvre failed. The cavalry moved around the first Byzantine line, leaving it for the infantry and charged the rear of their flanks. After a fierce fight the Byzantines were defeated, abandoned the battlefield and took refuge in Rusokastro. The Bulgarian army surrounded the fortress and at noon on the same day Ivan Alexander sent envoys to continue the negotiations. ==Aftermath==