The 39-year-old quickly moved past his American rival on the par-72, 7,215-yard Players Stadium Course with three birdies in a row between the second and fourth holes and went on to shoot a 67, 11-under for the tournament and four shots clear of the field despite needing an epidural injection to ease some pain in his neck.

"I had a pinched nerve and I had a numb arm for three weeks," Cejka said. "So they had to go in there and put some cortisone shot in the nerve, so it's healing better.

"It's still not 100% but I can feel my hand, so that's a good sign."

Poulter is lying two shots back in second place following a four-under-par 68, the Ryder Cup player compiling a round of five birdies and one bogey having started the day at five under.

Americans Kevin Na, John Mallinger and Jason Dufner were in the clubhouse on seven under after a 66, 71 and 70 respectively while David Toms shot a 70 to join them and Masters champion Angel Cabrera shot a 65 that also took him to four shots behind Cejka.

Henrik Stenson of Sweden also finished on seven under with a 69.

Crane briefly stayed in touch with fellow early starter Cejka but a double bogey at the par-four 18th left him with a 73, taking him back to six-under in a group also including another Swede, Richard S Johnson.

Camilo Villegas of Colombia had got to seven under before a double bogey at the par-five 16th led to a level-par 73, five-under at the halfway stage, and England's Paul Casey will also start the third round at five-under following a 69 that consisted of five birdies and two bogeys.

Sweden's Daniel Chopra staged a remarkable comeback from an opening-round 75 to shoot a 65 and end the day at four under alongside Englishman Brian Davis, following a 71, and world number one Tiger Woods of the USA, who shot a 69.

Justin Rose had got to six-under for the week with five to play before a double bogey and bogey sent him back to three-under following a 71.

Scotland's Martin Laird made it into the weekend with a level-par round of 72 that kept him at one under for the tournament while defending champion Sergio Garcia was at level-par following a 73.

Graeme McDowell was struggling over the closing holes, the Irishman falling to one-over with bogeys at the 14th and 17th holes before sneaking back to level-par with a birdie three at the last.

Ireland's Padraig Harrington posted a second consecutive 72 to remain at level-par, which was the projected cut mark, while Phil Mickelson, the 2007 Players champion, needed a birdie at the par-five ninth, his last hole, to reach the clubhouse at level-par following a 71.

Despite an eagle at the same hole, 2004 champion Adam Scott could only finish with 74, at one over for the week, but Luke Donald of England did enough on his back nine to sneak into the weekend.

Donald had been at three-over at the turn but a run of four birdies got him into the weekend and despite a bogey at his 17th hole, he stayed the course for a 70 to end the day at level-par.

Ireland's Rory McIlroy had also begun at two over but the 20-year-old shot a 77, finishing with a double bogey at the ninth, to end his week at seven-over.