Curtis was joined at 9-under-par 135 by Ryan Moore. Moore, who had a distinguished amateur career, fired a 5-under 67 in the second round to gain a share of the lead.
Reigning PGA TOUR Rookie of the Year Sean O'Hair posted a 3-under 69 Friday. He was joined in third place by Charles Howell III (69) and first-round leader Nicolas Thompson (72).
Curtis, who won the Booz Allen Classic earlier this year, started on the back nine Friday. He found water with his second at the par-5 11th and that led to a bogey.
He got that stroke right back on 12 as he chipped in for birdie. Curtis drained a long birdie putt at 15, then got up and down for birdie on 16 to move to minus-8.
Curtis rolled in a birdie putt from the fringe on the first. After four pars, he gave a stroke back with a three-putt bogey on six. Curtis recovered that stroke and gained a share of the lead with an up-and-down birdie on the par-5 eighth.
'I made it pretty easy on myself. I hit every fairway and the only bad shot I hit was the second shot on 11,' Curtis stated. 'Other than that, I played extremely well and made some long putts, which is nice. When you make long putts, it makes the game a little bit easier.'
Moore, the 2004 U.S. Amateur and NCAA Champion, also started on No. 10. He got going with long birdie putts on the 11th and 12th to move to 6 under. Moore settled in as he parred the next nine holes.
The two-time U.S. Amateur Public Links Champion dropped his approach inside 15 feet at the fourth and drained that birdie effort. Moore sank a 9-foot birdie putt on seven and two-putted for birdie on the par-5 eighth to gain his share of the lead.
'It was solid all the way around,' Moore admitted. 'I had definitely some good par savers throughout the day, but gave myself a lot of really good chances for birdie.'
Moore battled injuries early in the season, but he seems to be rounding into shape as the year winds down.
'It was a pretty up-and-down year to start out and then I went through some injuries and now recovery,' Moore said. 'I've had some good tournaments since the Buick Championship. I'm starting to move in the right direction. I feel like things are getting a little bit more consistent.'
Steve Stricker fired a 5-under 67 in round two. He stands alongside Robert Garrigus, Greg Owen, Kent Jones and Rory Sabbatini in sixth place at 7-under-par 137.
Defending champion Jason Gore is tied for 46th at 1-under-par 143.
The cut fell at 1-over-par 145 with 81 players moving on to the final two rounds. U.S. Ryder Cuppers Brett Wetterich and Chris DiMarco made the cut on the number of plus-1, while David Toms made the weekend at even-par 144.
Two other Americans going to the Ryder Cup -- Chad Campbell and Scott Verplank -- missed the cut by four and three shots respectively.