By Brian Keogh
Open champion Padraig Harrington was battling to catch the leaders in the $8 million WGC-Bridgestone Invitational last night.
The Dubliner, 35, began the day five shots off the pace on two over par at fearsome Firestone in Akron, Ohio.
But he found himself a massive eight shots adrift as Rory Sabbatini, 31, put in a blistering finish to his second round to lead on six under par.
Level par for his round with four to play, the South African reeled off a birdie hat-trick from the 15th to card his second three-under par 67 on the trot
That left him two shots clear of Masters champion Zach Johnson, who had six birdies and just one bogey in a sensational 65.
Johnson said: "This golf course is just about getting the ball on the fairway and today my score card showed that I played solid.
"I hit a lot of fairways and my putter started to work. You get it on line and they're going to go in. It's just about hitting those fairways."
Johnson, 31, needed only 27 putts and confessed that conditions were more difficult than in the opening round.
He explained: "The wind is probably a little more severe. It was just that I hit the ball a tad more solid today than I did yesterday. Even my misses today were good misses.
"I can't over-power this golf course and I really can't even attack it, but I can pick it apart."
Delighted with his strong finish, Sabbatini predicted that two more 67s would seal him the title.
He said: "If I shoot 12 under, I'm winning. I don't see anybody beating 12 under on this golf course.
"The way I look at it is I'd take even money right now shooting even par on the weekend. The course is only going to get tougher."
It was certainly a battle for major champion Harrington, who started brightly with birdies at the first two holes before the course bit back.
At the first, the world No 6 holed a raker from the the back fringe to get back to one over par and then rammed in a 26 footer at the second to surge into contention at level par.
He had to hole another 25 footer at the eighth just to save bogey after moving his second shot just 20 feet in the left rough and then dropped another shot at the ninth after another pulled tee shot.
It was just as tough for Ulsterman Darren Clarke as he mixed two birdies with four bogeys in a rollercoaster front nine to slip back to two over par alongside playing partner Harrington.
Ryder Cup star Paul McGinley was also suffering his share of ups and downs as he went to the turn in three over par before snatching a birdie at the 10th.
Back to four over par after 13 holes, McGinley's day started on a low when he ran up a double bogey six after a visit to the greenside lake at the third.
While he birdied the 200-yard fifth from 12 feet, he followed Harrington's example with back to back bogeys at the eighth and ninth before firing a wedge to just 10 feet at the 10th.
England's Paul Casey also had a tough day at the office as he crashed to a three over par 73 that left him six off the pace on level par.
World No 1 Tiger Woods bogeyed the first and birdied the second and while he dropped another shot at the sixth, he bounced back at the eighth and then parred the next four holes to trail Sabbatini by four shots with six to play.