George Pachymeres reported that during the Uprising of Ivaylo, Euphrosyne contacted her family in Constantinople to inform them that Ivaylo had arrived in the Golden Horde. Consequently, Michael VIII sent his son-in-law to Nogai, the former Bulgarian king Ivan Asen III who was married to Euphrosyne's half-sister Irene Palaiologina. Divided between the two contenders for the Bulgarian crown, Nogai initially hesitated and delayed his decision. However, Euphrosyne sided with Ivan Asen III, and Ivaylo was killed during a feast attended by both contenders. Later on, Euphrosyne requested from her husband to spare Ivan Asen III, the second pretender to the Bulgarian throne, from execution, which allowed him to flee to Asia Minor.