WIMBLEDON, England — All fortnight Wimbledon had been abuzz with talk of young guns and future stars — the teens and barely 20-somethings who brandished the big serves and go-for-broke tactics. But just as it seemed a new world order was at hand in men’s tennis, top-seeded Novak Djokovic and grass-court master Roger Federer reared up to snuff out any thought of insurrection and secure spots in Sunday’s championship.