Philadelphia - The Carroll Boy's Tennis team became the first-ever District 12 boy's champions in school history by defeating Masterman today, 3-2, in the district finals.  Carroll rallied for three consecutive match victories after dropping the opening singles matches.  Philadelphia Catholic League AA singles champion, Dan Nieves, clinched the win in straight sets (7-5, 7-5).  Doubles partners Mike Freidrich and Andrew Bulman scored a straight set victory (6-3, 6-4) while second doubles mates, Mike Fratoni and Pat Daly, duplicated the feat.   Carroll moves on to P.I.A.A. interdistrict play on Tuesday, May 12 vs. local tennis power neighboring Harriton High School.  The match will be played at 1:00pm at Perkiome Valley High School.