Shane Lowry rode a hot putter right into contention for the US PGA as he birdied the last to fire six-under 64 in the second round at Bellerive Country Club.

The 2015 WGC-Bridgestone Invitational winner has been struggling to put four rounds together this year, but he's now just three strokes behind leader Gary Woodland, tied for fifth on seven-under.

Lowry resumed on the second tee with eight holes of his delayed second round to complete and picked up three more strokes, rattling in a 25-footer at the par-three third before following a crucial, seven-foot par saver at the par-three sixth with birdies at the seventh and ninth.

"I knew the course was going to be somewhat playable this morning so I thought if I could come out and get two under for the last eight it would be a very good score," Lowry said. 

"To birdie the last and cover those holes in three under and shoot 64 was just, look I am delighted to be where I am. 

"I’m looking forward to the afternoon and tomorrow. If I keep playing the way I am, you never know where that might leave me tomorrow afternoon."

At the seventh, he hit a glorious three wood down the middle and fired a wedge to 18 inches.

He while he was disappointed not to birdie the par-five eighth after his pitch from left of the green failed to run out, he made amends at the ninth, firing a 173-yard eight-iron to just six feet to a tight back left pin before calmly rolling home the putt.

Lowry has hit the ball well from tee to green, but the key to his performance has been the shortest club in his bag.

He holed 124 feet of putts in round two and lies second in the strokes-gained putting statistics with just one miss from 32 attempts inside 10 feet.

After opening with a 69, he continued in that vein on Friday, picking up birdies from 22 feet at the 12th and 13 feet at the 13th and 17th before making another 13 footer for par at the 18th.

He pointed to his pave save that the sixth as key after his tee shot carried a few paces too far and ran down into a swale left of the green.

"Stuff like that in tournaments like this, when it is all said and done you don’t think about it, but when you look back, things like that are huge," h said of the uphill seven-footer that broke perfectly off the right edge.

"It's the putt you want to leave yourself, and I was clever with the pitch shot and then to go on and get a couple of birdies."

He admitted he was disappointed to be called in off the course by  Friday afternoon's thunderstorm but despite his 4:45 am alarm call ahead of the 7 am restart, he was pleased to reproduce his form of the first two days and take advantage of perfect conditions.

"I didn't think we were going to get called yesterday, and I was going along lovely," he said. "So I was probably a little bit disappointed. Got a good night's rest, went out this morning and did the business. It was nice. 

"Conditions were perfect. I mean, no real wind this morning and perfect greens.

"I had eight [to play]. I was on the second tee, which was a bit of a smelly tee shot to come back to, but I hit two nice shots in there and then holed a nice putt on the third, and that got me going, and I played lovely from there on in."

Lowry has had several early morning calls this week and admitted he wasn't leaping out of bed at the first alarm.

"I had to turn over," he said with a grin. "I set about four or five alarms. I think I got up about five past five. Got here at ten to six.

To be able to come back out this morning and play nicely was good. With eight holes left, there are a few tricky holes in there. The sixth hole is a pretty tough par three, and four and five are pretty tough as well. So to play those holes nice was good."

While he was brilliant with the putter, he might have also birdied the fifth and eighth but was happy with his 64.

"Yeah, like the eighth hole, I feel like I should have made birdie there," he said. "I thought the chip shot was a little bit unlucky, lands very soft. I hit a good putt as well instead on the eighth. 

"But to birdie, the last was lovely out here. I didn't think I had enough club to really get back to the flag. I didn't want to bring long into play. I hit just a perfect eight-iron there, and it was nice to hole the putt."

Lowry admitted in the build-up that he's feeling very comfortable in his skin after a tough period that ended with him taking a break from his caddie of nine years after the first round of The Open, where he missed the cut.

His younger brother Alan, an accomplished amateur, has taken holidays and leave of absence to stand in for four weeks with next week's Wyndham Championship their last event together.

Whether that's the reason for his more relaxed demeanour and better play he does not know, but he's happy he's playing well.

"Yeah, it's great. Look, obviously things haven't been going well for me this year," Lowry said. "The last few weeks have been good. I have my brother on the bag, and he's doing a great job, really enjoyed it. And now we're going out on a Saturday afternoon in the mix at the PGA, it's great. I have my dad here to watch. Look, it doesn't get much better."

Lowry said before the start that a score in the high single digits under par after three rounds would be in with a shout on Sunday.

Now that he's almost there, he wonders what the PGA of America will do to curb the low scoring not that there's much they can do with the greens still very soft.

"I think they may try to hide the pins the most they can in the afternoon. We just say, look, come out and hit the tee shot and walk after and see what happens after that."

Rory McIlroy picked up three shots in his last 11 holes to card a 67, sandwiching a chip in birdie at the 14th between tap-in birdies at the par-five eighth and 17th to move up to tied 25th on three-under.
 
"I didn’t have my best stuff out there; I think I only hit one green in the last six holes," McIlroy said. "But I guess I did what I needed to do. I need to tighten up my iron play this afternoon to give myself a chance. 

"Get the ball on the fairway, and you leave yourself a lot of eight and nine irons, but I wasn’t hitting them well enough. There are a lot of birdie opportunities out there, and I need to make a few of them."

The Co Down man's patience was exemplary as he made 16 pars in a row between his back nine on Thursday and his front nine on Friday before he broke the streak by getting up and down from a greenside bunker at the eighth, splashing out to two feet.
 
"It felt like the only way I was going to break it was by chipping in or a tap-in putt," he said.

Woodland leads by a shot from Kevin Kisner on 10-under with Rickie Fowler firing a 67 to join Brooks Koepka in a share of third on eight-under.

However, Pádraig Harrington and Paul Dunne missed the level par cut.

Harrington birdied the 18th and the third to get to one-under-par but double-bogeyed the fifth, finding the left rough before missing from close range for par after a layup, carding a level par 70 to finish one shot outside the cut mark on one-over.

"I struggled on the greens all week," said Harrington, who had just five birdies all week. "When you struggle on the greens, you can't afford to have a bad hole like I did there. 

"I hit a decent drive down the left but just caught the rough and had a bad lie. I laid it up and didn't hit a great pitch and missed the putt."

"When you play well and only have five birdies it's not a good sign."

Harrington plans to play the Wyndham Championship next week followed by the Czech Masters before taking a break ahead of a run of events in Europe.

Dunne shot a second successive, three-over 73 to miss the cut by six shots.

The Greystones player hit just six fairways over the two rounds, including only two in the second round, but was sixth for putting.