Humble, TX (SportsNetwork.com) - Andrew Putnam birdied six of the last seven holes on Friday and jumped into the lead at the Houston Open.

Putnam fired a 7-under 65 to finish 36 holes at 12-under-par 132. Putnam, who is winless on the PGA Tour, has missed the cut in five of his last seven tour starts. If Putnam goes on to win, he would earn the final spot in the field at the Masters next week.

Former champion Phil Mickelson carded a 67 to move into second place at minus-11. He was joined there by Austin Cook, who birdied his final four holes for a 7-under 65.

Graham DeLaet (67) and Luke Guthrie (68) are tied for fourth at 10-under-par 134 on the Tournament Course at the Golf Club of Houston.

Jordan Spieth and Mark Wilson both shot 66 on Friday and moved into a share of sixth place at minus-9. They were joined there by Hunter Mahan (68), J.B. Holmes (70), Victor Dubuisson (68) and Shawn Stefani (69).

First-round leader Scott Piercy struggled to a 2-over 74 and tumbled into a share of 18th place at 7-under-par 137.

Putnam, who won on the Web.com Tour last year, played the back nine first on Friday. He had eight pars and a birdie on the 17th.

Around the turn, Putnam began his surge starting with a kick-in birdie at the third. He made a 9-foot birdie putt at the fourth and followed with a 20- footer for birdie on No. 5.

Putnam poured in a 22-foot birdie effort at the sixth to move to 10-under. He joined Mickelson atop the leaderboard with a birdie at eight. Putnam capped his round with a 15-foot birdie putt on No. 9 to finish one clear of the field.

"I caught fire on the back nine, started making a lot of putts. These greens are so good out here, if you start rolling them on your line and seeing your line, you can make a lot of putts," said Putnam, whose brother Michael is tied for 12th at minus-8 after a pair of 68s. "I've played pretty good so far. I've kind of been a little loose with the driver, but this course is pretty wide open so you can do that."

Mickelson, the 2011 winner, got his round going with a 19-foot birdie putt on the second. He gave that right back as he 3-putted for bogey on the third.

The 44-year-old knocked in a short birdie effort at the fourth and made it two in a row as his 8-footer for birdie on No. 5 found the bottom of the cup. After three pars in a row, Mickelson drained a 24-footer for birdie at the ninth en route to making the turn at minus-9.

Mickelson dropped his approach at the 11th six feet from the hole and he made that for birdie. He birdied the 13th from eight feet out and moved to 12-under with a 22-foot birdie putt on the par-5 15th.

The five-time major champion hit a poor drive on the 17th and that led to a bogey. Mickelson closed with a par at the last.

"The golf course is in great shape as always. It's fun tournament, it's going to be a shootout. There's a lot of guys at 8-, 9-, 10-under par that are right there. It'll be a fun weekend," Mickelson said. "It's fun for me to put myself in position heading into the weekend to have a chance. That's an important thing for me heading into next week is to get in contention, to feel that pressure and get back to playing late on the weekends."

Cook traded a birdie for a bogey from the 10th to start his day. He birdied the 13th and 16th to move to minus-6. Cook started his second nine with four pars and a birdie on the third.

The 24-year-old, who is playing just his second PGA Tour event, started a hot closing stretch with a 43-foot birdie putt at the sixth. Cook birdied the final three holes, all from inside six feet, to grab a share of second place.

NOTES: Putnam has the 36-hole lead for the second time on the PGA Tour, with the other coming at the 2014 Shriners Hospital for Children Open, where he went on to share 33rd place ... Mickelson was the last player to win the week before the Masters, then win the Masters as well. He did that in 2006 when he won the BellSouth Classic, before winning his second green jacket the following week ... Luke Guthrie hit 30 consecutive greens in regulation, surpassing the season high of 27, which was set by Brandt Snedeker ... The cut line fell at 4-under-par with 71 players making the cut ... Among those that missed the cut were former majors champions Louis Oosthuizen, Justin Leonard, David Toms, Angel Cabrera, Martin Kaymer and Darren Clarke as well as Bill Haas, Lee Westwood and last year's winner Matt Jones. That makes it three straight years in which the defending champion missed the cut.