A fantastic scrap between the two real heavyweights of the Saudi-backed tour ended at the first play-off hole at Steyn City in Johannesburg on Sunday when DeChambeau drilled a remarkable three-wood approach from a soaking lie in the rough on the par-five 18th to set up his title-clinching birdie.
After a second win in a week following his Singapore triumph last Sunday, the American then broke down, as he revealed how he had faced personal off-course challenges during the week.
"A lot had happened in my life in the last week, I am so grateful for my team and everybody supporting me," said the .
"Golf is a fickle game, you work so hard at it your whole life and then you realise golf is just golf."
He and Rahm had finished on 26 under over the 72 holes, but DeChambeau had had to pull out all the stops to get up-and-down on the last hole to ensure his play-off opportunity.
It was a fittingly dramatic end to an amazingly well-supported event, featuring 100,000 spectators over the week.
They were particularly energised by the team format as DeChambeau's quartet, the Crushers, also featuring Paul Casey, Charles Howell III and Anirban Lahiri, won the event by a shot at a combined 76 under from the South African Southern Guards quartet.
There was such a remarkable Ryder Cup-like atmosphere that DeChambeau rated it the best LIV event of all and Casey said it even bettered the recent, hugely popular LIV Golf Adelaide event.
"I think everybody in SA should be so proud of what they've achieved here," said Casey.
"I've got to go on record -- and this is going to upset a few people -- I think this is the best LIV event. This is better than Australia in Adelaide - they're going to have to raise the bar now down in Oz."
In DeChambeau's final start before the Masters, the 32-year-old demonstrated what a danger he could be at Augusta with his fifth LIV victory, as did Rahm, who finished with an eight-under 63 to the American's 66.
Cam Smith looked in decent form too as he finished tied for 17th on 16 under after a 69. Marc Leishman (67) and Lucas Herbert (66) were joint-31st on 12 under, while Elvis Smylie's 74 saw him slip to joint-44th on eight under.
Their all-Australian Rippers GC team ended up eighth in the team contest.
