open (up) daylight
v. phr.— «Strong and composed, she showed no outward sign of weakening under the pressure and when she decided to go for home, 1 190 metres from the finish, she quickly opened up daylight between herself and the Irish girl.» —“McKiernan’s silver lining” by Peter Byrne in Bailbao, Spain Irish Times (Dublin, Ireland) Mar. 29, 1993. (source: Double-Tongued Dictionary)