South Korea's Im Sung-jae finds himself three strokes off the first-round lead at the second leg of the lucrative PGA Tour playoffs.

Im shot a two-under 68 to open the BMW Championship at Olympia Fields Country Club's North Course in Olympia Fields, Illinois, on Thursday (local time).

Im, who had three birdies and one bogey, is tied for 12th place with five others. Rory McIlroy and Brian Harman, a pair of major champions, share the opening round lead at five-under par.

Im is one of four South Koreans in action at the BMW Championship, the second playoff stop on the tour. The top-50 players in the FedEx Cup standings after last week's FedEx St. Jude Championship qualified for this week's tournament. And those who rank inside the top 30 after the BMW Championship will advance to the final playoff event, the Tour Championship, in Atlanta next week.

Im came into this week at No. 28 in FedEx Cup points. He is tied with Choi Kyoung-ju for the most appearances at the Tour Championship with four.

Kim Si-woo, the top South Korean in the FedEx Cup standings through last week at No. 17, shot a 71 with two birdies against three bogeys to tie for 30th place in the tournament. Kim's only Tour Championship appearance so far came in 2016.

Tom Kim, who was No. 18 in the FedEx Cup race, carded a 72, following a wild round featuring four birdies and six bogeys that put him in a tie for 40th.

An Byeong-hun carded an even-par 70 in the opening round, good for a tie for 23rd, with two birdies and two bogeys, as he tries to crack the top 30 after beginning this tournament at No. 38 in FedEx Cup points.

Since the FedEx Cup playoffs were introduced in 2007, only six South Korean players have competed at a Tour Championship: Im, Lee Kyoung-hoon, Kim Si-woo, Bae Sang-moon, Choi Kyoung-ju and Yang Yong-eun.

Where they qualify for the Tour Championship will also be important. Under the "starting strokes" system, the higher the players' position is in the FedEx Cup standings, the bigger the advantage will be for them at the start of the Tour Championship.

The FedEx Cup points leader will begin the season-ending tournament at 10-under, and the No. 2 player will start at eight-under, and so forth. Players between sixth and 10th will be at four-under at the start. The bottom five players in the top 30 will begin the tournament at even par. (Yonhap)