After the first round of the season finale, much remains to be decided as many of the top players in the FedEx Cup standings are also near the top of the leaderboard at the Tour Championship. Here's how things look after one round at East Lake, where Chris Kirk and Billy Horschel share the lead:
What it means: Kirk and Horschel played together in the day's final pairing as Nos. 1 and 2 in the overall standings, and they'll again be paired together Friday after matching rounds of 4-under 66. The elite field of 29 players didn't separate much in the opening round, though, as more than half the field will begin Round 2 within three shots of the lead.
Round of the day: Horschel successfully carried the momentum from his win last week at the BMW Championship, making it around East Lake in the opening round without a bogey. Horschel began with eight straight pars before three birdies in a five-hole stretch from Nos. 9-13, adding a fourth circle on No. 16. Horschel found 16 of 18 greens in regulation and appears eager to contend for a postseason trophy for the third straight week.
Best of the rest: Kirk entered atop the FedEx standings, and like Horschel he failed to drop a shot in his opening round. The Georgia alum birdied the first hole in front of partisan crowds in Atlanta, then added three more birdies including an unlikely chip-in at No. 17. After a win at the Deutsche Bank Championship two weeks ago, he's in the mix to become the first No. 1 seed to win the FedEx Cup since Tiger Woods in 2009.
Biggest disappointment: Hunter Mahan played good golf at the right time in order to earn a Ryder Cup captain's pick, but Tom Watson can't be pleased by his most recent performance. Mahan finished 64th at TPC Boston and followed that with a T-59 finish at Cherry Hills, and now the veteran is next-to-last after a disappointing 74. Mahan made three birdies but countered with seven bogeys, and now sits eight shots off the pace.
Main storyline heading into Friday: Kirk and Horschel are still the players to beat, as they were entering the week, but don't discount a pair of major champions that lurk in the distance. Watson is only one shot back after a bogey on the home hole, while Rory McIlroy put on a late rally to get into red figures, and the Ulsterman will begin the second round at 1 under as he - like Kirk, Horschel and Watson - controls his own FedEx Cup destiny and will lift the season-long trophy with a Tour Championship win.
Shot of the day: Kirk appeared to be making a mess of No. 17 and was well short of the par-4 green in two shots, but from there he turned a potential bogey into a birdie. His chip from 82 feet bounded up a ridge in the middle of the green before curling toward the hole, hitting the pin and dropping for an unexpected 3.