Without playing well , the 41 - year - old Scot led 4 - 0 at one point on Saturday .
Then 7 - 5 yesterday evening before Zhang responded , growing in assurance with each ball potted .
Without playing well , the 41 - year - old Scot led 4 - 0 at one point on Saturday and then 7 - 5 yesterday evening before Zhang responded , growing in assurance with each ball potted .