Final leaderboard (US unless stated):
-10 R Garrigus, R Karlsson (Swe), L Westwood (Eng)
-9 G Willis, S Micheel -8 H Slocum -7 B Mayfair
Westwood won at fourth hole of play-off
Westwood, 37, has recorded top-three finishes in the last three majors
England's Lee Westwood received a boost ahead of the US Open, which starts on Thursday, by winning the St Jude Classic after a three-man play-off.
The world number three made the most of a final hole meltdown by American Robert Garrigus to clinch his first PGA Tour title in 12 years in Memphis.
Garrigus needed only a six on the par-four 18th to win but took seven.
Westwood and Swede Robert Karlsson joined Garrigus in a play-off with Westwood winning at the fourth hole.
"It's definitely nice to win again," said Westwood, who has finished in the top three in the last three majors.
"Golf is a funny game. Sometimes it gives, sometimes it takes away."
The 37-year-old Westwood, who also tied for fourth in the prestigious Players Championship last month, will resume his quest to win a maiden major title when he tees off alongside world number one Tiger Woods in the first two rounds at Pebble Beach.
"I like being competitive before a major championship, to be competitive in a tournament and boost my confidence," said Westwood.
"This week was a little bit draining with the temperature it gets to here, but because I've been to Pebble Beach and done most of my preparation I can take it easy for the next three days."
Westwood's victory at the TPC Southwind was only his second career win on the PGA Tour and his first since 1998, despite 20 victories on the European Tour.
"In my career, I've had highs and lows," said Europe's number one, who slumped to 246th in the world in 2002 after topping the European money list two years earlier.
"I've dropped down in the world rankings and come back up it. So to be contending for golf tournaments is a real positive because I couldn't see a fairway or the golf course eight years ago."
Three shots behind overnight, Westwood laid down the gauntlet on an extraordinary final day in Memphis by hitting birdies at the second, third and fourth to race into a one-shot lead ahead of Garrigus.
However, Garrigus picked himself up, with birdies at eight, 10, 15 and 16 to give him a clear edge once again as Westwood could only register a string of pars.
A bogey at 17 from the Englishman seemed to ruin his chances once and for all, only for Garrigus's meltdown on the 18th to bring both Westwood and Karlsson back into the picture.
Garrigus then drove behind a tree to and made a bogey to drop out after the first hole play-off hole, while the two Europeans parred.
After drawing level on the 11th and 12th they went back to the 18th, and after a brilliant approach with a wedge, Westwood holed from five feet for a winning birdie - making him the first European to win the PGA Tour's third longest-running event.