The trio came in at 11-under-par 133.
Furyk, who has played only three events since returning from wrist surgery, shot a 5-under 67, while Andrade fired a 7-under-par 65 on Friday. Singh, the 1997 winner, only managed a 2-under 70 at Warwick Hills Golf and Country Club.
Olin Browne (70) and three former winners this season are tied for fourth place at minus-10. Carlos Franco, last week's winner at the U.S. Bank Championship in Milwaukee, shot a 67, while John Daly, who titled at the Buick Invitational, fired a 64 and Stewart Cink, the champion at the Heritage, carded a 7-under 65.
Tiger Woods, who is 0-9 in majors over the last two years, posted a 4-under 68 and is part of a group in eighth at minus-9.
'I'm right there,' said Woods, who won here in 2002. 'I'm two shots back, if I can just play the way I've been playing, you never know. There are some good names, but no matter who is on the board, you're going to have to make a bunch of birdies.'
Woods will be chasing the three co-leaders starting Saturday.
Furyk, No. 9 in the world rankings, began on the back nine at Warwick Hills and wasted little time in breaking into red numbers. He birdied three of his first five holes to race up the leaderboard, but his bogey-free play on the second nine is what got him into first.
He drained a 21-foot birdie putt at the par-3 third, then added another at No. 6 to join Andrade in a share of first.
'I like my spot,' said Furyk, who won last year's U.S. Open. 'I just need to keep making some birdies and keep firing some low numbers on the weekend. I'm happy with the way things went today.'
Singh did not play as well as his seven birdie and one eagle, first round of 63. He started on the back nine like Furyk, but collected his first birdie at the 14th. Singh added his only other birdie at the fourth.
Singh, ranked third in the world, switched from the belly putter to a more conventional putter this week. While his putting was not as strong as it was in the first round, Singh also struggled more with his iron play in Friday's second round.
'It didn't work as good as yesterday, obviously,' said Singh. 'But I hit it very close yesterday. I missed a lot of chances on the front side, but I don't know if I was tentative or what. You know, I'm surprised I'm still leading, but it's good to be leading still.'
Andrade, ranked slightly behind his co-leaders at No. 213 in the world, recorded four birdies in his first 11 holes, but fell down the leaderboard with a bogey at 12.
Andrade parred his next two holes before a fantastic run to close his round. He hit a 7-iron to 4 feet to set up birdie at the 15th, then made it back-to-back birdies with a tap-in birdie at the par-5 16th.
The Rhode Island native knocked a 6-iron 10 feet short of the hole at the 17th and Andrade rolled home the birdie putt. He wedged his approach to 4 feet at the last to polish off his fourth birdie in a row, and grab part of the 36-hole lead for the first time on tour since the Pennsylvania Open in 2002.
'Obviously when you finish with four in a row, it's pretty cool,' said Andrade, whose last win on tour came in Las Vegas four years ago. 'I'm ecstatic where I'm at and I'm looking forward to the next couple of days.'
Craig Barlow (69), Pat Bates (65) and Bob Tway (67) joined Woods in eighth place at 9-under-par 135.
The 36-hole cut fell at 4-under-par 140 and among those who did not make the weekend were: Shaun Micheel (143), who will defend his PGA Championship in two weeks, and Jeff Maggert (146), who is 10th on the current United States Ryder Cup points list.