PARIS, June 7 (Reuters) - Flavio Cobolli left everything on Court Philippe Chatrier as he chased a first Grand Slam title on Sunday, but the Italian admitted the pressure of playing on the biggest stage ultimately proved decisive in a heartbreaking defeat. The 24-year-old arrived at Roland Garros having never gone beyond the quarter-finals of a major tournament and left it as a Grand Slam runner-up, his reputation transformed despite falling one match short of the title.