Imran Tahir (R) celebrates Chris Morris after running out Sri Lanka’s Suranga Lakmal for a duck during the ICC Champions Trophy match between South Africa and Sri Lanka at The Oval in London on Saturday. Pic/AFP

Opening batsman Hashim Amla's 25th century in One-Day International (ODI) cricket and leg-spinner Imran Tahir's 4/27 helped South Africa overwhelm Sri Lanka by 96 runs here on Saturday to begin their ICC Champions Trophy campaign emphatically.