On May 17, 1971 — Roberto Clemente’s two-out, two-run, walk-off triple transforms a frustrating 5 – 4 loss to fifth-place Montreal into a sudden-death 6 – 5 decision, pulling Pittsburgh to within one game of the New York Mets. After failing twice in crucial spots earlier in the game, Clemente clubs Mike Marshall’s 1-1 pitch high off the wall near the 410-foot mark.
Source:
Baseball Reference May 17