BETHLEHEM, Pa. — Padraig Harrington finally knows what it’s like to overpower a golf course, and it has him on the verge of a U.S. Senior Open title.

Harrington reached both par 5s in two, hitting 5-wood to 7 feet on the 608-yard 12th hole at Saucon Valley, and his 5-under 66 enabled him to open a 5-shot lead going into the final round of the Senior Open.

Starting the third round with a 1-shot lead over Steve Stricker, his Ryder Cup captain foe from Whistling Straits, Harrington birdied the opening two holes and was on his way.

He was at 12-under 201, 5 shots clear of former U.S. Senior Open champion Gene Sauers, who birdied the last two holes for a 68, and PGA Tour Champions rookie Rob Labritz (69).

“When you’ve got a lead like this — in not even a perfect world, but in dreamland — you think you’re going to go out there and play well and run away with it, which is a possibility,” Harrington said. “I could play good tomorrow and have a nice, comfortable day. I could play average tomorrow, and someone will have to come at me. Or I could play badly tomorrow, and I’ll still have a chance.

“I’ve basically given myself a lot of hands to win this.”

Stricker couldn’t keep up after an opening birdie, and the par 5s is where the winning U.S. Ryder Cup captain really lost ground.

Harrington drilled a fairway metal into 25 feet on the 568-yard sixth hole, while Stricker hit a tree and had to flight a chip under the branches. He came up short of the green and made bogey. It was a 2-shot swing when Harrington two-putted for birdie for a 4-shot margin.

And then on the 12th, Harrington blasted his 5-wood over the corner of the rough to a pin tucked on the left side. Stricker’s wedge went just through the green, his chip down the hill was too strong and he made another bogey. This turned out to be a 3-shot swing when Harrington holed the eagle putt.

Harrington, who turned 50 last August and is playing his first U.S. Senior Open, stretched his lead to as many as 9 shots. He had two bogeys over the last four holes, his first dropped shots since the opening round.

Otherwise, it was a pure power show, even for the 50-and-older set. The way he swung with force during rehearsal swings, reminiscent of Bryson DeChambeau, showed how much Harrington has emphasized speed in his swing to get more distance.

“Padraig is tearing it up,” Sauers said. “He’s playing a 6,500-yard golf course, and I’m playing a 7,500-yard golf course.”

Harrington was never like that in his prime, relying on a clean strike and plenty of grit to capture the British Open in successive years (2007-08) and the 2008 PGA Championship at Oakland Hills.

Two-time U.S. Open champion Ernie Els had a 67 and was 7 shots behind.

“He’s got a lot of length out here,” Els said of Harrington. “He’s got a lot of length out here. He’s probably the longest off the tee on the Champions Tour. When he has it under control, like he has this week, you’ve got to watch out. It’s good to see. He’s playing with a lot of freedom.”

Stricker never found his putting stroke all day and shot 73, leaving him 8 shots behind along with Steven Alker and 68-year-old Jay Haas, who each had a 71.

“It wasn’t really what I had in mind today,” Stricker said. “No. 6 kind of jumped up and got me again today. I hit a beautiful 3-wood. I thought I could cover that tree that’s on the corner, and rattled in there and kicked it over into the woods and ended up making a bogey there when you’re trying to get a birdie opportunity there.

“And just some sloppy play at times,” he said. “I didn’t make any putts, didn’t get it up and down. I thought I hit it a little bit more solid today and just made too many mistakes.”