The two were tied at seven-under-par 133 after two rounds.
Woosnam and Hallet had tied at 275 after four rounds.
If the scores are tied after four rounds, a golden word tiebreaker will occur.
If tied after 2 rounds, a "slide-off" takes place with only one roll per family; the most points wins.
If they are tied after 10 rounds, there will be a tie breaker.
If the score is tied after five rounds, the rotation will begin again until a winner is decided.
They had finished the regulation 72 holes Sunday tied at six-under 282 after four rounds.
They were tied with each other after two rounds, and played together for the final 36 holes, during which they shot 65-65, and 65-66, respectively.
Tied for the lead after three rounds, he shot a round of 72 and finished tied for third.
Blackwelder, tied for the lead after two rounds, struggled today in the heat.