Tway, who won this event in 1986, played the back side first at the TPC at Sugarloaf and picked up two birdies over his first six holes. Tway then two-putted for a birdie at the par-5 18th to begin a barrage that vaulted him into the lead.
The 43-year-old hit a pitching-wedge to three feet for a birdie at the first and drained a 10-foot putt for a birdie at the following hole. At the par-4 third, Tway hit a sand-wedge to 15 feet for his fourth birdie in a row to reach 8-under.
Tway moved to 9-under with a birdie at the fifth but three-putted the par-3 eighth for a bogey to secure the early clubhouse lead.
'I think we had a little bit of an advantage being first off today,' said Tway. 'Any time the conditions are like they are, the earlier, the better.'
Tway, who also won the PGA Championship in 1986, is seeking his first victory on the PGA Tour since 1995.
'I'm pleased with the way things are going,' said Tway, who is making his 22nd appearance at this tournament. 'I've played well the last month. I just figure the more times that I give myself a chance, then maybe one time I'll sneak in there. That's kind of how I'm looking at it.'
Janzen had a later tee time and also started on the back half. The two-time U.S. Open champion tallied an eagle, two birdies and a bogey over his first nine holes to make the turn at minus-6.
Janzen ran home a long putt for a birdie at the third and two-putted for birdie at the very next hole to tie Tway in first.
He took the lead outright with a birdie at the sixth but found trouble at the par-3 eighth. Janzen's tee ball found a greenside bunker and he left his second shot short in the fringe. The 38-year-old bogeyed the whole en route to a round of 67.
'It's been fun the last two days to hit it really well, manage myself around the course, chip well and putt well all at the same time,' said Janzen, whose last tour victory came in 1998. 'I felt like I've been pretty close most of the year. A couple times on the west coast I played really well and it's just a matter of making a few more putts here and there.'
Goosen, whose victory here in 2002 was his second on tour and his first since the 2001 U.S. Open, had four birdies and two bogeys for a round of 70.
'The course obviously played a bit tougher today,' said the South African. 'In general I'm pretty happy with the game.'
Chris DiMarco, who held the lead after the opening round, managed an even-par 72 to finish three shots back at 5-under-par 139. DiMarco was joined by Esteban Toledo, Billy Andrade and Carl Pettersson in a tie for fourth.
The 36-hole cut fell at 2-over-par 146 with 76 players qualifying for the weekend.
Phil Mickelson, who won this event in 2000, failed to make the cut in his return to the PGA Tour after a month-long break for the birth of his third child.
Mickelson struggled with a 79 on Friday to finish at 8-over-par 152.
'I have played well here,' said Mickelson. 'I felt, coming in, I wasn't as comfortable heading into this competition as I wanted to be. I wasn't in a very patient frame of mind.'
Scott McCarron, who won this event in 2001, also missed the cut at 7-over-par 151.