At 20 under, Kevin Na is still topping the leaderboard at TPC Summerlin. But there are some new faces applying pressure. Four-time PGA TOUR winner Tim Herron has entered the picture with a quartet of front nine birdies to reach 19 under, one shot behind Na. Herron has a pair of top-10 finishes this season and a third would lock up a 2012 TOUR card for the man currently ranked No. 105 on the money list. Na’s fellow Vegas-are resident and playing partner, Nick Watney, is still two back and has been joined by Tommy Gainey, who has posted back-to-back birdies to get to 18 under. Robert Garrigus, who joins Watney and Na in the final group, is even through six holes and four shots off the pace.