Micheel, who won the PGA Championship in 2003 for his only major tour title, finished Thursday with a 5-under-par 67. He is one stroke ahead of Jorge Campillo, Robert Rock and Danny Willett. Another seven players are at 2-under.
Winds and rain hampered players who had early starts Thursday with Francesco Molinari -- one of those at 2-under -- posting the best score from the morning tee times.
The up-and-down play was shown by Rock, who had two eagles, four birdies, two bogeys and a double bogey on his round. Campillo had a more serene bogey-free round while Willett carded six birdies and two bogeys.
Micheel opened with a birdie but then had a bogey at the second hole. He had birdies on three of the next four holes before a bogey at No. 8. A birdie at the ninth hole allowed him to make the turn at 3-under.
After three pars, Micheel again had three birdies in a four-hole span. His drive on the 18th hole found a sand trap, however, and he finished the day with a bogey.