Padraig Harrington was unable to follow up his stunning opening round at the Transitions Championship in Florida but is still only two behind American Jason Dufner at the end of day two.
The Irishman carded a course-record ten under par 61 on day one, the lowest round of his career, but he could only make a two over par 73 after carding three bogies and just the one birdie.
That left the three-time Major winner in joint second spot at the midway point of the tournament on eight under, two adrift of Dufner and level with William McGirt.
Dufner, still searching for his first US PGA Tour win, recorded a second successive blemish-free round of 66 after picking up birdies at the first, third, fifth and nine to turn in 32, before adding another birdie on the 11th.
Dufner's compatriot McGirt added a 68 to his opening-day 66.
England's Luke Donald was one of five players tied for fourth spot on seven under par.
After turning in one over par, the world number two had a superb start to the back nine with four birdies in the opening five to lift him into contention.
Sergio Garcia was in the group on six under after his second consecutive 68, while Justin Rose is one shot further back after a 70.
