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.