Europe's Number One, who has been part of the field at Sawgrass only three times in the last seven years, added a sparkling 65 to his opening 67 for a halfway total of 132 which was only two outside Greg Norman's tournament record.
With Phil Mickelson, the man who pushed him into second place at The Masters Tournament, and World Number One Tiger Woods deep in the pack Westwood now looks a good bet for his first win in America since 1998.
Nor is Westwood under threat from last week's Quail Hollow winner Rory McIlroy or three-time Major winner Padraig Harrington, both of whom missed the cut.
A first prize of more than £1.1million is on offer this weekend and deep into the second day Westwood was one ahead of Italian Francesco Molinari and Japan's Ryuji Imada.
Third, third and second in the last three Majors, the Worksop golfer said: "I keep coming back. Don't keep knocking me - I'm not going to go away.
"I'm just going to keep trying until one of them goes my way.
"A victory here would be incredibly important. You get that sort of tingle when it's getting close."
Westwood stepped up the pace with an eagle and six birdies.
The eagle came with a brilliant drive and five iron to three feet on the 16th, the hole where he had been in the water for a bogey six on his previous visit.
Molinari matched Westwood's 65, while Imada shot a 66 and they were joined late in the day on 11 under by American Heath Slocum.
Woods, who missed the cut by eight shots last week, hit ugly drives on the 11th and 14th and dropped three strokes on them, but he also had four birdies in a weird six-hole stretch.
Three under at the turn he had hopes of making up more lost ground on the front nine, but could not make any further progress and so will start his third round nine adrift.
At least he had stayed around for 36 more holes, though, and avoided what would have been a second successive early exit for the first time in his career.
"I wasn't quite as sharp," he said after what was only his eighth round since the sex scandal which sent him into hiding in November.
"It's still a process. The three wood on 14 (into water) I tried to stop, but I got to the point where I couldn't.
"I felt like I putted better, but unfortunately I was just a little bit too far away from the holes."
McIlroy missed the cut on his debut last year and said after a 72 for one over: "You can't see fairways when you are on the tee and I find it hard to line up."
The European Tour challenge was proving formidable once again - as well as Westwood and Molinari, Australian Robert Allenby and England's Luke Donald reached eight under.
Northern Ireland's Graeme McDowell is just inside the top ten on seven under, one ahead of Y E Yang and Adam Scott, with Sergio Garcia, Fredrik Jacobson and Anders Romero amongst those five under.