CHICAGO • US Open champion Dustin Johnson fired a nine-under 63 on Friday to match fellow American Roberto Castro for the lead after the second round of the BMW Championship.
Johnson set a course record at the 7,516-yard Crooked Stick layout in Indianapolis to stand on 14-under 130 after 36 holes in the penultimate event of the season-ending US PGA Tour play-offs.
He said: "Any time you shoot that good a score, you putt really well and I did just that."
Castro, who is of Peruvian and Costa Rican heritage, fired his second consecutive 65 as he bids for his first Tour triumph.
"It's a good start," he said. "There are still a lot of holes but it's a good way to get into the weekend."
England's Paul Casey (66) was third on 133, one stroke ahead of Americans J.B. Holmes (65) and Chris Kirk (66).
Johnson, who switched putters only on the eve of the event, is aiming for his 12th PGA win.
"I really didn't make the decision until right before the first round," he said. "I practised with it a little bit.
"I just felt like I have been putting it pretty well, but I was just struggling to get my putter on the line that I was seeing.
"So I just grabbed one of these putters and started rolling it. It's the same one Jason Day uses.
"I played with him the last two weeks and saw him make enough putts and I was like, well, I got to try one at least."
The top-30 finishers in the season points race after this event will qualify for the Tour Championship in Atlanta.
Day 4: StarHub Ch204, 11.55pm