Rory McIlroy's decision to go with the flow on the greens and return to a familiar putter has given him a chance to end a near 18-month victory drought in the Arnold Palmer Invitational at a firm and fast Bay Hill.

Six shots behind Henrik Stenson and Bryson DeChambeau starting the day, the Co Down man married his best ball-striking round of the week to his revitalised putting to card a five-under 67 that leaves him alone in third on 10-under-par.

As for his wedge play, a 148-yard dart to two feet for a closing birdie leaves him just two shots behind the Swede, whose 71 gave him a one-stroke advantage over DeChambeau (72) on 12-under as Tiger Woods also birdied the 18th for a 69 to share 10th, five shots off the pace.

As St Patrick's Days go, it was a great one for McIlroy, and also for a straight-hitting Graeme McDowell, who continued his resurgence with a bogey-free 69 that leaves him tied 14th on six-under.

"I worked on my swing a bit and found a feeling, something I could go with this week and hopefully beyond," he said of the transformation of his game from last week's missed cut in the Valspar Championship to this week's excellence, especially on the greens.

"I freed up a little bit with my putting, just became a little more instinctive with that; a little more reactive. I came into this week really positive — it's a golf course I've played well before — and I just felt a little more in control of my game and in control of my swing.

"I felt that if that could translate from practice to the golf course, I could have a good week."

Wielding his driver and fairway woods like offensive weapons yesterday, he missed just two fairways and rebounded from his lone bogey at the 11th by hitting a five-iron to seven feet to set up an eagle three at the 12th.

Buoyed by that 238-yard missile, he then single-putted the last five greens to be second for strokes-gained putting for the week, picking up two birdies in his last three holes using a 34 1/4 inch putter again - a set up that's brought him four major wins so far.

Those single putts included a tap-in from two feet at the 18th, where he hit a wedge stiff and appeared pleased that he and caddie Harry Diamond and settled on "a flat-out wedge" from 148 yards.

A swing thought that reminds him to keep his backswing tight — "feeling like it's a three-quarter swing" — eradicated a two-way miss and his wedge play was more precise.

He still missed seven greens with his irons but thanks to a chat with Brad Faxon at the Bear's Club last weekend about getting away from putting mechanics and trying to be more reactive rather than over-precise on the greens, he was impressive again with the blade.

"I guess I was using the line on the ball and maybe just getting bogged down a little bit too much in mechanics, trying to hit perfect putts," he explained. 

"The hole is quite wide; you don't have to hit perfect putts for it to go in. So just trying to be a little imperfect, just be a little more free."

It doesn't sound like he's ditched putting coach Phil Kenyon and taken on Faxon, but simply found a little key that could help at next week' WGC-Dell Match Play and at Augusta National in three weeks' time.

"It was a great chat," he said. "He lives down in that area. And honestly, it was more of a psychology lesson rather than a putting lesson. 

"I didn't really hit many putts on the green. We just had a bit of a chat about it. We just tried to go into this week a little more free, a little more instinctive, reactive to my target. Just a little more into the putt than the stroke I guess. 

"It is nice to have him there to call if I ever need. I think the work I have done has paid off in terms of the mechanics of the stroke and it was more of a mindset to go out there and be a bit more free and it has worked this week."

McIlroy' round included birdies at the fourth, ninth, 16th and 18th and he sounded excited about having a chance on Sunday. 

"I was pretty pleased with my play over the first couple of days, and we had pretty much perfect conditions today. Even though the course was firm, you needed to take advantage of them, and I played probably the best golf I've played all week. 

"A 67 was great to get in with, and I am happy to have a chance going into tomorrow."

With Justin Rose and Ryan Moore just three shots behind and the top 13 covered by six strokes, a low round on Sunday could be worth much gold

"I'm going to have to shoot a low one tomorrow and probably get a little bit of help," said Woods, who mixed six birdies with three bogeys and a handful of excellent par saves. "But my responsibility is to go out and shoot a low one first."

He added: "I played well, scored well, it was a good day all around. Can't complain about anything I did today. I really hit the ball solidly, I controlled it, and I hit a lot of beautiful putts, some went in, some didn't."

The key for McIlroy and Woods will be to avoid mistakes and take care of the par-fives on a course that will play firmer and faster than anything the players have seen this year.

That hasn't always been McIlroy's favourite set up but he's comfortable at Bay Hill — he's been T11, T27 and T4 in his first three visits — and he's clearly found something in practice and taken it to the golf course

"I've loved Bay Hill from the first time I've played it," he said. "When I got here for the first time in 2015, I regretted not coming here before. I felt like it set up really well for me. I can take advantage of the par fives. It's the way Tiger always played this course - he killed the par fives and played conservatively the rest of the way around. 

"It's always been a good golf course for me, and I have had some good results here. Hopefully, I can draw on those feelings tomorrow."

As for McDowell, he's slowly building confidence and looking to get some more on Sunday after an immaculate 69, hitting all 14 fairways 

If anything, he's finding the greens a little too slick for his style of putting.

"I'm a pretty aggressive putter, and these greens are not allowing aggressive putting," he said. "They're quite slick, there's not a lot of grain on them, and there's not a lot of friction on them really, and putts can get away from you quite quickly.

" So putting's been tough this week because of the pace of the greens. I let a few get past me out there today, but to go bogey-free, it's a decent Saturday, very happy with it, would have liked a few more to get myself more in touch, but where my game's at right now, days like today are very important for me."

He added: "I'm happy with the way my game is trending at the moment and I have got to keep pouring confidence back into the game."

McIlroy, no doubt, would echo those sentiments.