Graeme McDowell was left to rue bogeys on the 17th and 18th as he finished in a share of fourth place two behind winner Joel Dahmen at the PGA Tour event in the Dominican Republic.
The 41-year-old, who won the Corales Puntacana Resort and Club Championship event in 2019, shot a five-birdie final round of 69 which left him on 10 under.
However, his closing dropped shots ultimately undid his chances.
Dahmen finished one ahead of Puerto Rico's Rafael Campos and Sam Ryder.
US player Dahmen, who secured his first top-10 major finish at the PGA Championship in 2020, held on to claim his maiden PGA our title despite a nervy final round of 70.
Canada's Michael Gligic shared fourth place with Northern Irishman McDowell.
Despite missing out on victory, McDowell described his week as "massive progress" following his dismal run of form since the sport resumed last summer following the first lockdown.
"It's great to feel disappointed with a top 10 because it's been a really, really rough three months this year," said the 41-year-old, who moves up 13 places in the world rankings to 111th spot as a result of his performance in the Dominican Republic.
"It's actually been a rough stretch since last June, since we came back after the break. I really haven't played the type of golf I know I'm capable of.
"It's been a tough run and this is really a light at the end of the tunnel this week, so it's really important that I sort of frame this up the right way," added McDowell, who was ranked as high as fourth in 2011.
The 2010 US Open champion's career looked right back on track when he won the Saudi International 13 months ago which helped move him back in the world's top 50 before the sport was halted as a result of Covid-19.
Ireland's Seamus Power finished tied for 54th spot on one over after carding a 73 on Sunday, two positions above European Ryder Cup captain Padraig Harrington who ended his tournament on three-over after a final round of 73.
The Dominican Republic event featured players who did not qualify for the WGC Matchplay event in Texas.