Norwegian Casper Rudd reached his first US Open semi-final with a scintillating win over Italian Matteo Berrettini on Arthur Ashe Stadium.
Victory lifts the 23-year-old to number two in the world rankings.
Ruud, who reached this year's French Open final, will take the top spot if he wins his semi-final against either Nick Kyrgios or Karen Khachanov, who play each other later on Tuesday.
More to follow.
