Yes Sir, under reverse charge mechanism you shall be under obligation to pay full service tax on the sponsorship amount and without any abatement thereof.
As per Notification 25/2012 ( The Mega Exemption Notification ), only following services are exempt :-
Services by way of sponsorship of sporting events organized,-
(a) by a national sports federation, or its affiliated federations, where the participating teams or individuals represent any district, state or zone;
(b) by Association of Indian Universities, Inter-University Sports Board, School Games Federation of India, All IndiaSports Council for the Deaf, Paralympic Committee of India or Special Olympics Bharat;
(c) by Central Civil Services Cultural and Sports Board;
(d) as part of national games, by Indian Olympic Association; or
(e) under Panchayat Yuva Kreeda Aur Khel Abhiyaan (PYKKA) Scheme;