Fred Funk has joined overnight leaders Ben Curtis and Sergio Garcia on six under after setting the Firestone course alight with a scintillating 62 today.
Funk, two over this morning, posted an eight-under 62 to tie for the lead with Ireland's Darren Clarke and Tiger Woods one shot further back. The leading quartet are just beginning their second rounds.
Padraig Harrington got off to a perfect start in his second round but had to endure mixed form after that and sits on four over for the tournament.
The Dubliner was only joint 68th, but with no change still back home, where his wife Caroline is expecting their first child at any time, he said he intended to stay for the final two rounds.
Funk, having pitched in on the first, holed from a bunker at the short 15th and with that joined Curtis and Garcia, both of whom had yet to start with leaders out last from the second round onwards.
Three closing pars meant an eight under par 62 which was only one off the Firestone record set by Jose Maria Olazabal in 1990 and equalled three years ago by Woods.