Billy Horschel leads Rory McIlroy in Tour Championship

Billy Horschel has finished the second day of the Tour Championship two shots clear of the field at the top of the leaderboard in Atlanta.

The American carded a four-under round of 66 for the second round in a row, leaving him two strokes ahead of Chris Kirk, Jason Day and Rory McIlroy, who all sit on six-under for the tournament.

The world number one had been off the pace in his opening round, but three solid putts in a row this afternoon, as well as a tee shot landing in a spectator's pocket, helped the Northern Irishman to a round of 65.

Kirk, who was tied at the top with Horschel at the start of the day, was unable to match his opening round, slipping to joint second, while Day carded three-under for the second time at the event to remain in the hunt.