Rookie Carson Young extends lead at PGA's Puerto Rico Open
Young, who shot 63 in his opening round, had an eventful final nine holes, on the front nine, making four birdies and two bogeys including on his final hole where he drove into the rough.
Young, who had to battle away on minor tours before getting his card for this season, had made just three cuts in 12 starts on the main tour coming into this tournament.
"I didn't quite have it like I did yesterday obviously, but it was still good," he said.
"My tee shots weren't quite the way I wanted them. I got into trouble a good bit, but my short game really saved me," he added.
His ability around the green was most evident on the par-4 seventh where he holed in from the greenside bunker.
"I just hope the putter stays hot and get that driver sorted out the next couple days and I should be in good shape," he said.
Colombian Nico Echavarria (67) and American Paul Haley (66) were both four strokes behind Young.
Harry Higgs shot an eight-under-par 64 to move within five strokes of the lead alongside fellow American Ryan Gerard who shot 67.