Justin Rose was forced to settle for a share of the halfway lead at the BMW Championship with Mark Wilson after an intriguing second round at Cog Hill.
The Englishman had led by two shots after a superb eight under par 63 on Thursday which saw him produce nine birdies and just one bogey, finishing one shot outside the course record held by former World Number One Tiger Woods.
He was in good form again to produce a round of 68 and move to 11 under, but it was Wilson who enthused the crowd as the American followed his opening 65 with a consistent 66.
The pair are two shots clear of Webb Simpson after the American's 68 left him on nine under.
Rose was out in 33 having birdied the third, eighth and par five ninth, with a bogey on the seventh. He did the same on the 13th but eagled the 15th and picked up another birdie on the next.
That gave him a one shot lead on 12 under with Wilson having set the clubhouse target, but a bogey on the 18th dropped him back into a tie with local favourite Wilson.
Australian John Senden put himself alone in fourth, just three off the lead on eight under, with a 66 to follow his 68. Bill Haas and Robert Allenby were two shots further back.
Englishman Luke Donald atoned for his first round of 75 with a 66 to move to one under, joined by the likes of Martin Laird, Hunter Mahan, Rickie Fowler and Sergio Garcia.
