Deutsche Bank Championship leader Brendon de Jonge said his six-under 65 on Friday surprised him as much as it did everyone else.

The Zimbabwean leads at TPC Boston by two shots after the first round, having not registered a top-20 result on the PGA Tour since doing so in back-to-back events in April.

"It came completely out of nowhere. It's out of left field," De Jonge told a news conference of his seven-birdie round.

"I felt like I played pretty good at the [US] PGA [Championship], made the cut and then struggled on the weekend and then missed the last two cuts, just really couldn't put my finger on it. 

"I wasn't doing anything really badly, but wasn't doing anything great... struggled to put a score up. 

"A pleasant surprise today."

De Jonge helped the International team win two points at the 2013 Presidents Cup, which United States went on to win by three, but lamented a lack of improvement since earning a place in the prestigious team event.

"I was looking to build on The Presidents Cup. I felt like I really played nicely for the entire week," the 35-year-old said. 

"To have the season I had last season following up The Presidents Cup wasn't what I wanted by any means. And then I start off this season great. 

"I lost in the play-off early in the year and had a couple of really good chances to win, which is what I was looking for.

"But obviously two years later the big thing was to get that first win, which I haven't. That's still the glaring omission. 

"I need to get back to playing the sort of golf that I have for a long time where I've been consistent and been in contention a lot, which is what's been lacking recently."

De Jonge has never won on the main US circuit, his lone title coming on the second-tier Nationwide Tour in 2008 - but he did lose in a play-off at the McGladrey Classic in October.