Thomas Bjorn posted a three-under-par 68 to take a one-shot lead into the third round of the World Cup of Golf at Royal Melbourne.
The 42-year-old Dane book-ended his round with bogeys but five birdies in between secured a narrow halfway advantage over Kevin Streelman.
The American opened with birdies on his first four holes but a bogey at eight and a double-bogey at the next saw him come back to the field.
Three shots further back are Jason Day (70) of Australia and Portugal's Ricardo Santos, who matched Streelman's 69 for a two-round total 138.
Scotland's Martin Laird and Stuart Manley of Wales both carded one-over 72s to share fifth place alongside Matt Kuchar (68) of the United States and Japan's Hideto Tanihara (67).
In the team event Streelman and Kuchar lead the way on 10-under-par, three shots clear of Danish duo Bjorn and Thorbjorn Olesen with Japan and Australia a further four strokes adrift.
After the round a satisfied Bjorn said: "There were a couple of things that happened on the golf course today that really tested me. I three-putted the first, so got caught a little bit there.
"But after that I patiently worked my way into the round and played very solid. Maybe not quite as good as yesterday on the front nine, but on the back nine I played awesome.
"Obviously it was disappointing to bogey the last, but if you'd asked me when the ball was in the air, I would've said you couldn't have hit a better golf shot."