The incentive is huge at the Riyadh Golf Club with the winner of Saturday's 36-hole final qualifying for the LIV league next season.
Also at stake is a purse of $US1.5 million ($A2.3m). The top-10 finishers, including ties, also stand to earn full exemption into all 2025 events on the International Series, sanctioned by the Asian Tour.
Buchanan and Coletta both shot four-under 67s on Friday to make the field.
Among their rivals for the big prize are South African Branden Grace, and brothers Scott and Kieran Vincent of Zimbabwe.
The event began Thursday, but Grace and the Vincents were among 29 players exempt into the second round on Friday. All three are former full-time LIV Golf members who were relegated at the end of 2024.
A 15-time winner worldwide, including one LIV event, Grace became the first player to shoot a round of 62 at a major championship (2017 Open Championship).
Scott Vincent had the best round of the day at Riyadh Golf Club, an eight-under-par 63.
But there isn't room enough for both Vincent brothers in the 2025 LIV Golf season with only the top finisher qualifying for next season.
"Of course I want him to do really well," Scott Vincent said of his brother, "but at the same time I want to be just one step ahead of him, and I'm sure he wants the exact same thing."
Kieran Vincent shot a 65 Friday and Grace had a 66. Kieran Vincent earned a promotion into the league at this event last year, when three spots were available.
The only American to qualify for the final day was Ollie Schniederjans, who won a 6-for-1 tiebreaker in three playoff holes.
"I want to play against the best players in the world again," said Schniederjans, a former top-ranked amateur.
"I think I'm coming back to (form) - I'm fully healthy. I've been through a lot, and I just want to prove myself again and get that opportunity."
Among the former LIV players who did not play well enough Friday to move on were Finland's Kalle Samooja and American wild card Hudson Swafford.
The 20-player field is as follows:
Jack Buchanan (Australia), Ben Campbell (NZ), Gunn Charoenkul (Thailand), Brett Coletta (Australia), Branden Grace (South Africa), Jeongwoo Ham (South Korea), David Horsey (England), Taichi Kho (Hong Kong), Lee Chieh-Po (Taiwan), Daihan Lee (South Korea), Richard T. Lee (Canada), Soomin Lee (South Korea), Steve Lewton (England), Suteepat Prateeptienchai (Thailand), Max Rottluff (Germany), Ollie Schniederjans (US), Kieran Vincent (Zimbabwe), Scott Vincent (Zimbabwe), Borja Virto (Spain), Jeunghun Wang (South Korea).
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