Padraig Harrington fired a 5-under-par 66 on Saturday to extend his lead to five strokes at the U.S. Senior Open in Pennsylvania.
Harrington sits at 11 under, five ahead of Gene Sauers (68) and Rob Labritz (69) after shooting the joint-lowest round of the afternoon's play.
The Dubliner, who took a one-stroke lead into the third round, hit five birdies and an eagle and would have been further clear, only for two late bogeys to act as blotches on his card.
"I'm not really sure what to think," Harrington said.
"I know I missed some chances out there to be lower, and I know I got a few breaks here and there and did some good stuff.
"When it comes to this course with a five-shot lead, I've given myself plenty of options to win this tournament. That's the important thing.
"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, who is still looking for his first win on the Champions Tour, posted his lowest 54-hole total playing on the seniors circuit with 202.
Additional reporting: Reuters