"There's life in the old dog yet", Poulter said after beating American Beau Hossler on the first hole of a sudden death playoff at the Golf Club of Houston.
"I had a good read on my putt on the final green in regulation as Beau's putt was on much the same line and I knew it was going to break a fraction right and it did, so I rolled it in at the right time", said Poulter.
"Tuesday morning I made the decision to come and play".
Hossler then flared his approach into a green-side bunker and Poulter safely reached the green in two.
After his whirlwind third-round 65 which rocketed him to joint third position, Greg Chalmers shot a disappointing nine-over-par 81 to finish in a tie for 70th.
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The Englishman displayed ferocious competitiveness and his experience at the elite level proved to be the difference as the duo replayed the par-4 final hole with Hossler chipping out of a bunker into the water to all-but end his chances. Hossler, a PGA Tour rookie, recorded his third top-10 finish of the season.
It was just Spieth's second top-10 finish of the year, but it comes just one week before the Masters, where he already has a win and a runner-up placing in his career. To come here this week, I was exhausted and frustrated. I was patient. I waited my time.
"To come here this week, I was exhausted, I was frustrated", said Poulter, who packed his bags after shooting 1 over on Thursday, assuming he would miss the cut. That was a month after Poulter led Europe to a stunning turnaround in the Ryder Cup by making five straight birdies to win a fourballs match and give Europe momentum to overcome a four-point deficit.
Hossler did everything right until the playoff. "It's a bummer, but I'm very proud of the way I played".
Three-time major champion Jordan Spieth finished tied for third after posting a 6-under-par score of 66 on Sunday - going 16-under-par for the tournament. "I'm super excited. It's been a rollercoaster the last couple of years to be honest, to be down where I was has been tough". "This was by far the most comfortable I've felt in that final pairing or near contention, so I've proven myself now that I can win out here without a question of a doubt".