From Brian Keogh in Miami

Tiger Woods produced a brilliant putting display as he scorched to a superb six under par 66 to grab a two shot lead at the halfway stage of the WGC-CA Championship at Doral's Blue Monster in Miami

As Padraig Harrington hit a two under par 70 to get to remain six off the pace on one under par, the World No 1 knocked in six birdie putts and then saved a brilliant par from 10 feet the dreaded 18th to lead on seven under from Australian Rod Pampling, who carded a fine 69.

“Stevie noticed something we didn’t like in my stroke - but we fixed it,” said Woods, who had just 26 putts, six fewer than he took in the first round. “And lo and behold I was able to really putt it by the end.

"It all started at nine, where I had about and eight footer for par and I was able to make that and it was nice to have something positive happen. All of a sudden I was able to make three in a row.”

Overnight leaders Henrik Stenson and Robert Allenby had a bad day at the office with the Swede hitting just four fairways and dropping shots at the last two holes for a 73 as the Australian made just one birdie in a 74.

"I didn't drive the ball as well as yesterday and that put me in trouble," Stenson said. "But I am still in decent shape for the weekend and hopefully it will be better tomorrow."

A closing bogey by Australian Aaron Baddeley forced him to settle for a 71 and relegated him to a seven-way share of third place with Stenson, Irish Open champion Thomas Bjorn, Americans Zach Johnson and Charles Howell and the South African duo of Ernie Els and Trevor Immelman.

But Harrington made a move in the right direction when he fired four birdies and two bogeys in a solid 70 that left him with an outside chance of mounting a title challenge.

Harrington said: "I am not that far behind because I feel I have a good day in me and I haven't had that yet. The two bogeys I made were very slack bogeys but the rest was pretty good.

"I hit the ball well all day and I think 70 is a reasonably fair representation of the way I played. My game is really showing up the fact that I have been two weeks away and each day it will get better and better.

"I just need to get back into the swing of things, play a few rounds and get competitive. Let's wait and see over the next two rounds if I can get a couple of good scores in there. I am playing well and I would just like to be mentally sharper."

After an opening 73, Harrington looked set for another frustrating day when he duffed his 230 yard approach into the water at the par five 10th.

The Dubliner knocked his 40 yard pitch to six feet and saved par but missed 12 foot birdie chances at the 11th and 12th before lipping out from just four feet for par at the short 15th.

But he hit back straightaway with the putter, holing for birdie from five feet at the 16th and 16 feet at the 17th to get back to level par for the tournament.

A great par save at the 18th, followed by a 16 foot birdie at the par five first, put him in red figures again.

But he then three-putted from the back of the tough, par-four third, leaving his first putt eight feet short of the hole.

He was in more trouble at the 378 yard fifth after finding sand behind the pin but splashed out to eight feet and sank the putt.

But it wasn’t long before he edged under par again thanks to a 25 foot bomb at the sixth before parring his way home.

Aussie Pampling holed out from 155 yards for an eagle two at the sixth on his way to a 69 a solo second place behind Woods.

But there was frustration for Irish Open champion Bjorn, who cruised to the turn in two under par to share the lead on six under before imploding on the par five 10th.

Four putts from 40 feet cost the Dane an ugly double bogey seven but he was still pleased to get round in level par 72 and trail Woods by just three shots after a four-week break from the game.

"These things happen and I think every player in the field has had one in their lives," Bjorn said. "It was my turn today and while I bogeyed the last I am still in the tournament."