Smith’s final round of 69 included a costly bogey at the par-5 last hole at TPC Boston but ultimately left him at 13 under and one shot behind runner-up Justin Rose.
But Smith's strong showing has moved him to 8th in the FedEx Cup standings and a certainty to make the Tour Championship field of 30 at East Lake.
The finish comes on top of his share of 3rd place at last week’s Northern Trust Open, resulting in collective earnings of US$1.2 million in those two events alone and over US$3.4 million this season.
Smith has also advanced to Number 32 in the world ranking the highest of his career to date.
Smith has benefited by the arrival of his Australian coach Grant Field last week, the work he has done clearly evident in his performances over the past two weeks.
“I had my coach come in last week, we worked on a few things,” said Smith earlier this week. “Really got back to my roots and what I do best. Spent a lot of time around the chipping green and putting green last week. Everything is looking in shape.”
Despite an early bogey today, Smith worked himself into a potentially winning position when he birdied the 16th hole to get to 3 under for the day and at that point he was within just one of the leader, DeChambeau.
DeChambeau, playing behind Smith on the golf course, would birdie the 15th and par in to secure his third PGA Tour victory of 2018 and second FedEx Cup Playoffs win in a row.
The American takes a commanding lead in the FedEx Cup standings and will move to 7th in the World Ranking; the first time he's broken into the top 10 in his short pro career.
The 24-year-old put his great run down to the consistency he has been seeking. "Consistency has been a big thing for me," he said.
"I've been trying to get that week in and week out, and I was able to kind of figure something out last week on the putting green, and that's kind of progressed me to move forward."
Marc Leishman was the next best of the Australians behind Smith in 21st while Adam Scott was 49th and Jason Day missed the cut.
All four Australians are through to this week's BMW Championship in Pennsylvania but at this stage only Day and Smith are guaranteed a start at the Tour Championship.
Leishman in 22nd place in the FedEx Cup standings and Scott in 48th position will need to play well at the BMW to ensure their passage to Atlanta.
RULES: LOOSE IMPEDIMENTS IN A BUNKER
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