Rory McIlroy lost ground during the second round of the BMW Championship in St Louis on Friday, slipping five strokes behind the tournament leader. The Northern Irishman began the day tied for the lead after opening with a strong six-under-par round. However, a more difficult second-round score of one-under 69 left him trailing the front-runner heading into the weekend.

American golfer Wyndham Clark seized the outright lead following a flawless Friday performance. Clark carded a bogey-free round to reach 12 under par overall, making him the only competitor in the field to avoid a single bogey across the first 36 holes. He holds a slim one-shot advantage over compatriot Gary Woodland, who sits in second place at 11 under.

Reflecting on his performance after signing his scorecard, McIlroy noted that scoring conditions remained favorable despite a shift in wind direction. He observed that the greens continued to accept approach shots well and the fairways provided additional roll. Although he acknowledged that his ball-striking was not as sharp as it had been during the opening round, he expressed satisfaction with his resilience.

McIlroy highlighted a series of crucial par saves on the back nine that prevented his score from slipping further. His lone blemish of the day came via a mistake on the par-five eighth hole. To address his inconsistencies, the Masters champion announced plans to spend his afternoon working on his swing at the driving range.

Further down the leaderboard, several other notables remain in contention. JJ Spaun occupies third place at 10 under, while Sungjae Im and Chris Gotterup share fourth at nine under. A group containing Patrick Cantlay, Michael Thorbjornsen, Collin Morikawa, Russell Henley, and Maverick McNealy sits a stroke further back at eight under alongside McIlroy.

Among the European contingent, England's Justin Rose reached four under par by the halfway stage. Scottish player Robert MacIntyre and English golfer Matt Fitzpatrick are tied at three under, while Tommy Fleetwood sits one stroke behind them at two under. Aaron Rai rounds out the notable grouping at one under par as the tournament reaches its midpoint.

Reporting based on coverage first published by BBC Sport. Read the original report at BBC Sport.