Spieth among leaders at Colonial

Fort Worth, Texas (SportsNetwork.com) - Masters champion and world No. 2 Jordan Spieth fired a 6-under 64 in Thursday's first round and he shares the Crowne Plaza Invitational lead with Kevin Na, Boo Weekley and Ryo Ishikawa.

Spieth, playing in his home state of Texas, has already picked up two of his three PGA Tour victories this season, including the Masters. Weekley won here in 2013 for his third victory and has not won since. Na has one career win and Ishikawa has none.

Ian Poulter joined the leaders at minus-6 late in his round before falling back a shot. He is tied for fifth with George McNeill at 5-under 65.

Nine more players are one shot further back following 4-under 66s at Colonial Country Club.

Defending champion Adam Scott struggled to a 2-over 72 and is tied for 86th.

Spieth, playing for the first time since missing the cut at The Players, started his day off well by rolling in birdies from 25 and 12 feet at one and two, respectively. Following four straight pars from No. 3, Spieth continued his hot putting with a 14-foot birdie conversion on seven.

Making the turn at minus-3, Spieth kept going strong with a 22-foot birdie on 10. A gain at 15 pulled Spieth within one of the lead and another long 19- footer for birdie at the last tied the 21-year-old atop the leaderboard.

"I'm comfortable enough hitting my 9-8-7-irons into the green right now," Spieth said. "They're so receptive that you can still fire them right at the flag, so I was able to lay back, where I maybe pushed it and got into trouble in past years."

Na, playing the back nine first, holed back-to-back birdies on 11 and 12. He later added his third gain from four feet at 16 and closed his opening nine with a bogey on 18.

A birdie from 18 feet on two got Na back on track. After a trio of pars from three, Na finished on fire with three birdies in his last four holes, all of which were on putts from inside 10 feet.

"It was different weather than what we expect out here. It was chilly, a bit breezy and wet," said Na. "I started off great, hit a lot of good shots. I felt like my iron play was in "A" performance today, and I made some great putts when I needed to for par."

Weekley, also starting on the back nine, made birdies on 10, 12 and 14 before making the turn with six straight pars from 15. Back-to-back birdies from 14 and 26 feet on three and four had the former champ up to minus-5.

The 41-year-old finished up strong with four straight pars from five and a 13- foot birdie on No. 9 to close out his round.

"I drove it well today. Not really swinging at it real good right now because of my back, but other than that, it was overall, we just tried to manage it knowing that we couldn't hit full shots, so we went down a club and felt like we just punched it around the golf course and I made some putts," Weekley stated. "Made a lot of putts actually. I didn't make some, I made a lot."

Ishikawa joined Spieth and Weekley as the three leaders to go bogey-free on day one. Birdies on 13, 16 and 17 had Ishikawa rolling on his opening nine. It was more of the same on the closing nine as he made gains on one, eight and nine to join the leaders at minus-6.

NOTES: Despite a delay of three hours before play was able to get under way due to dangerous weather, every group was able to finish their first rounds. A total of 1.3 inches of rain fell overnight in Fort Worth ... Since his Masters win, Spieth has not notched a top-10 finish. He has seven, including two wins and two runner-ups, on the season ... Na's win came at the 2011 Shriners Hospitals for Children Open ... Weekley had a collective putting distance of 151 feet, nine inches on day one.