NEWTOWN SQUARE — For the most part, the second round of the AT&T National was a struggle at an Aronimink Golf Club that is becoming more and more challenging. But it’s probably safe to say that nobody experienced a more anxiety-filled day than tournament organizers and CBS Sports, who had to sweat it out for six-plus hours on Friday wondering whether Tiger Woods was going to make the 36-hole cut.

The planet’s most recognizable athlete ultimately made it, barely, thus averting what would have been a major calamity. But Woods will head into the weekend a full 10 strokes behind 36-hole leader Justin Rose, who seized a 1-stroke lead over Jason Day and Charlie Wi thanks to a masterful bogey-free 6-under-par 64.

“I didn’t really go out there with the intentions of going low, so to speak. The round just evolved and happened,” the South African native said.

At 7-under 133, Rose is in position to notch the second victory of his six-year PGA Tour career just four weeks after finally getting his first at the Memorial. But Rose, 29, is just five days removed from a final round collapse at the Travelers Championship in Cromwell, Conn., where he held the 54-hole lead and finished ninth.

“Closing out a golf tournament is difficult,” Rose said. “You do learn things, and depending how long it takes until you give yourself another situation whether you really learn something, you’ve got to practice it for it to become natural.”

Thanks to his shaky putter, Woods failed to make a move on Friday. But Rose certainly did with four birdies in a six-hole stretch on what ended up being a splendid back nine 31. He rolled in back-to-back 20-plus-footers at Nos. 12 and 13 to get it going, and then followed with two more at 16 and 17.

“It didn’t feel like a complete round of golf in terms of I didn’t miss a shot,” Rose explained. “But I think mentally it was probably one of my better rounds of golf. I just felt very patient. Even when I didn’t hit a good shot, I accepted it. I didn’t try to force the issue and get bullied by the golf course. So from that perspective things clicked.”

Of the four first round leaders, only Day managed to keep pace. His 2-under 68 included just one boogie, and he finished strong with a birdie at 16 and a long par-saving putt at 17. Not bad for a guy who said he hit the ball awful.

“I only hit five fairways but at least my putter was there to back me up,” the 22-year-old Australian said. “I’ve got to prop a few things up for the weekend to make sure I hit some fairways. I know I can’t keep shooting under par with the way I have been hitting it.”

At 6-under 134, Day shares second place with Wi, who holed out from 166 yards with an 8-iron for eagle on the par-4 12th en route to a 65. The South Korean’s performance this week has been a surprise because he has struggled all season long with just one top-10 to his credit and five missed cuts so far in 2010.

“The pins are really difficult today, and going out in the afternoon the greens were really firm out there,” Wi said. “There were a couple times when I went for the pin and went over the green, and I could have really kicked myself. But I kept telling myself to be patient, and I was able to roll some putts.”

Charley Hoffman is another surprising challenger. With just one top-20 in 14 starts heading in, Hoffman carded a 67 and is just 3-shots back in fourth place along with surging Jeff Overton at 4-under 136. Both stressed how difficult Aronimink is playing.

“I didn’t really know what to expect going into this week, but definitely when you got out here the rough was even longer,” Hoffman said. “They cut it down a few inches on Tuesday evening to make it a little more playable. But it definitely has a major feel out here.”

Overton missed the cut in four of his first six starts this season, but is clearly coming on with three top-3 finishes since late April. His only blemish of the day was a bogey at No. 9.

“The course is tough,” said Overton, who is looking for his first PGA victory. “If you miss the fairways you’re in some pretty bad trouble. (But) if you hit the fairways the ball is running enough where you’re hitting some short irons in and you can make some birdies.”

There are several proven veterans lurking, and Australian Robert Allenby is at the head of the list. A four-time winner on the PGA Tour, Allenby has three runner-up finishes this season and looks like he a serious contender so far. He carded a 67 on Friday despite some trouble off the tee, and is in sixth place at 3-under 137 along with seven others.

“I was in the rough a lot off the tee,” Allenby said. “I don’t know why but I didn’t have the confidence with my driver. (But) I have 100 percent confidence with my irons, so every time I was on the fairway I hit it close and I made birdie.”

The rest of the group sitting 4-strokes back includes Ryan Moore (70), John Mallinger (70), Kris Blanks (68), Brian Gay (70), J.B. Holmes (67), Nick Watney (71) and Bo Van Pelt (68), who’s father, Bob, was a fifth-round draft pick in 1967 by the Philadelphia Eagles out of Indiana University.

In all, 29 players are under par and remain in contention, including local favorites Jim Furyk (70) and Sean O’Hair (68), who are tied for 17th place at 1-under 139. And that number swells to 37 if you include an additional eight players at even-par 140.

“I am very surprised (seven)-under is leading after two days,” day said. “I’m guessing that single digits is going to win, so there are a loot of guys still in play. Even par can still win.”

That most likely bodes poorly for Woods, who shot a 70 and made the cut without a single stroke to spare at 3-over 143. With 36 holes to play, there are a whopping 63 players between Woods and Rose, the leader.

“Greg (Norman) always said that if he started the day six back on Sunday, he could still win the tournament and that is certainly within reach,” Woods said.

Woods’ second round was much like the first, which is to say it was a frustrating day on the greens that ended with a thud. Back-to-back birdies on his 12 and 13th holes of the day provided just a temporary lift as Woods boogied two of his final five holes.

“I am driving it on a string right now, and that’s fun,” he said. “But if you don’t make putts, no matter how good you hit the golf ball, you’re not going to shoot good scores.”

To contact staff writer Neil Geoghegan, e-mail ngeoghegan@dailylocal.com.