Koepka, saying he had learned his lessons from last month's Masters when he led by two going into the final round before a collapse opened the door for Jon Rahm to grab the Green Jacket, began the day with a one shot advantage and would not let go.

He carded a three-under 67 for a two-shot victory over Scottie Scheffler and Viktor Hovland. The win gives Koepka a fifth major and third PGA Championship to go with back-to-back wins in 2018 and 2019.

With Koepka clinging to a one-shot lead, the turning point came at the par four 16th where the big-hitting American had a birdie and Hovland a double-bogey after trouble in a fairway bunker, opening up a four-shot cushion.

The win will also be remembered as a landmark moment for LIV Golf, Koepka's major victory the first by a member of the controversial Saudi-bankrolled venture providing badly needed validation.

For all the magic produced by golf's biggest names at Oak Hill none could match what Block, an unknown club professional, conjured up.

Already a fan favourite before the final round teed off, Block, one of 20 teaching professionals in the field, added to a Rocky-like Hollywood script when his tee shot at the par-three 15th soared into the air and slammed straight into the cup without even rattling the flagstick.