Australian veteran Steve Elkington dropped a shot on the final hole but still remains in contention for his first PGA Tour win in more than a decade, two strokes behind Padraig Harrington at the halfway mark of the Transitions Championship in Florida.
The 47-year-old has not won since the Doral Ryder Open in 1999 but a top-10 finish in the Puerto Rico Open last week has him full of confidence.
Elkington, who finished tied for second at the PGA Championship in 2005, is six-under for the tournament and on track to regain the card he lost after a horror 2009 season.
Ireland's three-time major winner Harrington produced a six-under-par 65, his low round of the year, for an eight-under total.
With first-round leader Garrett Willis crashing to a 77, Harrington heads into the closing 36 holes one ahead of Americans Jim Furyk and Bubba Watson, Swede Carl Pettersson and defending champion Retief Goosen.
But World Match Play champion Ian Poulter bowed out on four-over after a second successive 73 in his final Tour event before next month's Masters.
Poulter needed to play the last six holes in level par to make it through, but went into the lake at the short 13th and finished with two more bogeys.
Harrington, without a Tour win since he won back-to-back majors at The Open and US PGA two years ago, grabbed seven birdies.
Starting on the back nine the Dubliner, who missed Wednesday's pro-am to attend a St Patrick's Day dinner hosted by President Obama at the White House, pitched to two feet on the 11th and then struck a 185-yard approach to four feet at the 16th.
He then had to hole from only 20 inches, eight feet and 10 feet on the first, third and fifth greens and after his only dropped shot at the next he found the target from eight and 10 feet again at the seventh and ninth.
Harrington, joint third in the WGC-CA Championship in Miami on Sunday, was tied for top spot at that point, but in the group behind him Furyk bunkered his drive down the ninth and bogeyed to match Pettersson's bogey-free 68.
"I'm capable of winning in the form I'm in," said Harrington. "Am I in my best form? No. Am I getting there? Yes."
"You put yourself out there. That tests where your game is at. Some weeks the results happen and you get a win and some weeks they won't."
"I've played tournaments where I've played great coming down the stretch and not won and I've played tournaments where I've played average and won."
"Because I don't know so many of the shots here I have to keep hitting at the flags and it seems to be working quite nicely."
"The greens are superb and the wind was predictable, so it was a good morning for scoring."
Adam Scott and Mathew Goggin are in a share of 18th place at three-under with Nick O'Hern a further stroke back.
John Senden and New Zealand's Tim Wilkinson are at one-under.
Geoff Ogilvy, Jason Day, Nathan Green, James Nitties and Rod Pampling all just made the cut at two-over.