Rory McIlroy is nine shots off leader Keith Mitchell at the halfway stage of the CJ Cup in Las Vegas with Shane Lowry a further eight strokes adrift.
McIlroy followed up his opening 68 with a bogey-free 67 in Friday's second round to move up to nine under overall.
The 32-year-old started well with a birdie on the first, before picking up further shots at six, seven and nine to gather momentum at the beginning of his back nine.
That proved less eventful for the Co Down native but he dropped no shots before a birdie finish on the par 5 18th.
Lowry carded an improved 70 in the second round but remains 17 shots off the summit on one under par.
After a bogey on the third, the Offaly man rallied with birdies on the 11th, 13th and 16th in a bogey-free back nine.
Meanwhile at the summit of the limited-field event of 78 players, Mitchell backed up his impressive opening day with a near-flawless second round to take a commanding five-shot lead.
After carding a 62 on Thursday, the American flew up the leaderboard on Friday with an eagle and seven birdies en route to a 64. His only blemish was a bogey on the par three 11th.
Mitchell heads into the weekend on 18 under, five shots in front of a four-strong chasing pack which includes former Masters winners Adam Scott and Jordan Spieth.
USA's Rickie Fowler, enjoying an upturn in form, joined England's Tyrrell Hatton in a tie for sixth on 12 under with the latter splitting nine birdies with two birdies in a 65.
Hatton is closely followed by compatriots Paul Casey and Ian Poulter, who shot 65 and 67 respectively to sit one shot back on 11 under.