Former champion Justin Thomas overcame testing conditions to set the clubhouse target on day two of the 104th US PGA Championship.
Thomas, who lifted the Wanamaker Trophy at Quail Hollow in 2017, carded a second-consecutive 67 at Southern Hills for a halfway total of 134, six under par.
That took the world number one a shot ahead of overnight leader Rory McIlroy, who was among the later starters on Friday as he continued his bid to win a fifth major title and first since 2014.
