Refer to the input text as context and select the correct relationship between 'Syriza' and 'Alexis Tsipras' from the available options.
Options: creator, chairperson, chief executive officer, director/manager

Greek Prime Minister Alexis Tsipras faced down a revolt by rebels in his leftists Syriza party to win parliament's backing for a second package of reforms required to start talks on a financial rescue deal.
chairperson