Paul Casey has tied the PGA back-nine record with a stunning display on day two of the HP Byron Nelson Championship in Irving, Texas.

Casey was in danger of missing the cut when he reached the turn on one over for the day, and two over for the tournament, but six birdies and an eagle saw him complete the back nine in just 27 shots. From flirting with an early departure Casey now sits just two shots off leader Brendon Todd.

Casey is just the eighth player in PGA tour history to shoot 27 on the back nine.

"The seal was broken when I got to 10," Casey said to pgatour.com. "It just spiraled from there."

"I like to think I would be pretty good at shooting low rounds of golf through the past," Casey said, "but certainly nothing like that."

Padraig Harrington is 4 under for the tournament, with back to back rounds of 68 on his first two days. Harrington is 4 off the lead.