Rory McIlroy wasn't going to let one bad shot ruin his round.

The world's No. 1 knows he's perfectly capable of making up ground on the competition with 54 holes remaining in the Wells Fargo Championship.

"If I can play the same sort of golf and get rid of the mistakes it will be close this week," McIlroy said Thursday after an opening-round 70 for a 2-under par.

McIlroy is five shots back of leader Robert Streb after making a double-bogey on the par-3 17th hole over water.

He appeared on the verge of a late run at the leaderboard when his tee shot hit the rock wall in front of the green and his ball caromed high into the air and into the water.

"One big mistake," McIlroy said.

McIlroy had just made par on No. 16 by hitting a 9-iron pin high from 166 yards. He went with an 8-iron from 178 yards on No. 17, but it wound up not being enough to carry the water when his ball got held up in the wind.

Despite the error, McIlroy said overall he was pleased with his round.

"I did what I wanted to," said McIlroy, who won the event in 2010 for his first PGA Tour title. "I took advantage of the par 5s and made birdie on a couple of par 4s."

McIlroy said he was pleased with his tee-to-green play entering the tournament, but vowed to be more aggressive with his putter this week.

He putted well for the most part, although left a birdie chance short on the 16th hole.

"I wasn't thinking so much about trying to hold the putter, trying to make a good stroke," McIlroy said. "I made a couple of nice ones."

Phil Mickelson had his troubles, too, after a fast start.

Lefty opened with three birdies, but had a double bogey on the 18th hole when his tee shot wound up in the creek on the left side of the fairway. He shot 71.

Mickelson has long expressed his affinity for Quail Hollow, saying it suits his game perfectly. Yet, he is winless in 11 tries, although he has come close with five top-5 finishes.

He was off to a rousing start, sinking birdie putts from 6, 9 and 12 feet to start the back nine, drawing roars from the crowd. But the putts wouldn't fall after his initial burst.

"I turned a 66 into a 71 today," Mickelson said.

Mickelson, who missed the cut last week at The Players Championship, insists his game "isn't that far off."

While Mickelson faded after his strong start, Streb didn't.

He enters the second round with a one-shot lead over Patrick Reed and Kevin Chappell.

After tying for 30th at The Players, Streb set the early pace with two quick birdies on the back nine and played a bogey-free round.

His 65 was the second-best opening round score of his brief PGA Tour career. He found his putting stroke last week at TPC Sawgrass and it was right there again at Quail Hollow.

"It's the first time in a while I feel like I have my putter working," Streb said.

It didn't hurt that he caught a few breaks along the way.

On the par-5 seventh, Streb hit a pitch shot from 10 feet off the green too hard, but the ball hit midway up the flagstick and dropped 4 feet from the hole, leading to an easy birdie.

"I smashed the flag," Streb said with a sheepish grin.

While many of the fans were heading for the parking lot to call it a day, Chappell turned in a strong finish with an eagle on the par-5 seventh and a birdie on the eighth to move into a tie with Reed for second place.

Reed spent time tied for the lead, but couldn't maintain it after failing to save par on No. 17 when his tee shot landed in the sand.

Defending tournament champion J.B. Holmes put himself in position to become the first repeat winner in the tournament's 13-year history by opening with a 69.

"I'm feeling really good about my game," Holmes said.

Many of the world's top players skipped the event, including Players winner Rickie Fowler, Tiger Woods, Jordan Spieth and Bubba Watson. Ernie Els withdrew because of a muscle strain.