Chalmers made a lightning start to the Quicken Loans National on the PGA Tour at Congressional overnight.
The 40-year-old Western Australian, who had had just one top-10 finish this season, carded a five-under par 66 to lead all comers, as Tiger Woods made his return to tournament golf after two months' absence because of back surgery.
Chalmers birdied the final three holes, and rode a white-hot putter all day, having just 25 shots with the short stick. "You've got to do that to shoot a low score,'' he said. "I put a new 915 Titleist driver in this week and I think I hit every fairway on the first nine, and I hit all but two on the second nine and one was by a couple of feet. I really drove the ball the best I have all year. That was kind of exciting. That set up the rest of the round.''
It was a good day for the Australians. Stuart Appleby, Geoff Ogilvy and Marc Leishman all broke par, as did rookie professional Oliver Goss (70). Jason Day played with Woods and carded a 73.
Meanwhile Woods began slowly with a 74, but was happy to be back on course.
"The back's great," Woods said. "I had no issues at all — no twinges, no nothing. It felt fantastic. That's one of the reasons why I let go on those tee shots. I hit it pretty hard out there.''