March 3 (Reuters) – Legal professionals for two previous 21st Century Fox executives accused of bribing South American soccer officers assailed the reliability of the government’s star witness on Friday, as their 7-7 days demo draws to a near. Carlos Martinez and Hernan Lopez are charged with wire and securities fraud conspiracy for allegedly scheming to pay out tens of tens of millions of dollars in bribes to secure lucrative broadcasting legal rights for global soccer tournaments. Cooperating witness Alejandro Burzaco testified that his former company companions knew about and accredited the bribes. A lawyer for Martinez instructed jurors in Brooklyn federal court on Friday that Burzaco ran the plan…