Dustin Johnson builds one-shot Boston lead after first round
|Dell Championship first-round leaderboard|
|-5 D Johnson (US); -4 K Stanley (US), M Leishman (Aus), S Garcia (Sp), J Rahm (Sp); -3 K Na (US), L List (US), B Harman (US), J Dufner (US), J Blixt (Swe), G Murray (US)|
|Selected others: -2 P Mickelson (US), R Fowler (US); -1 P Casey (Eng); level A Scott (Aus), J Thomas (US), I Poulter (Eng); +1 J Spieth (US), R Knox (Sco), R McIlroy (NI), H Matsuyama (Jpn); +3 M Laird (Sco), B Koepka (US); +4 J Day (Aus)|
World number one Dustin Johnson carded a five-under 66 to take a one-shot lead after the first round of the Dell Championship at TPC Boston.
The 33-year-old, who beat Jordan Spieth in a play-off to win last week's Northern Trust Open, is seeking his fifth title of the season.
Masters champion Sergio Garcia shares second after six birdies in his 67.
Defending champion Rory McIlroy, who has not won in 2017, had three birdies, two bogeys and a double in his 72.
The Northern Irishman's last win was in the Deutsche Bank Championship last September, which was his first PGA Tour title for 16 months and his first tournament success since the Irish Open four months earlier.
The Dell Championship is the second of the four FedEx Cup events, with the top 70 after Monday's final round progressing to Lake Forest in Illinois for the BMW Championship starting on 14 September.
'I've got a lot of confidence now'
Starting at the 10th, Johnson holed from 35 feet for birdie on his opening hole, the first of his five birdies, and hit a seven-iron approach from 220 yards to four feet to set up an eagle on the par-five ninth.
"When you win, you're playing well, so it gives you a lot of confidence," said Johnson. "For me, that was one thing that was probably lacking a little bit the last few months.
"I wasn't seeing the shots that I wanted to see. I wasn't hitting them consistently. But after last week, I've got a lot of confidence now."
Johnson's playing partners Spieth and Justin Thomas - The Open and US PGA champions respectively - were much further down the leaderboard.
Spieth was three over par for his first seven holes before finishing with a 72, while Thomas had 16 pars, one birdie and one bogey in a level par round.
Instead, Johnson's closest challengers were Garcia, Australia's Marc Leishman, American Kyle Stanley and Jon Rahm of Spain - each of whom are a shot back.
Spain's Garcia posted five birdies on the front nine and managed to scramble a par on his final hole.
"I made some nice putts here and there early on," Garcia said. "And the ones that I didn't make, they looked like they were going to go in. So a lot of positives."