Jessica Pegula fights back to clinch place in first grand slam final

Jessica Pegula is in to the US Open final (Julia Nikhinson/AP)

Jessica Pegula staged an impressive comeback to reach her first career grand slam final at the US Open.

The American, seeded sixth, looked to be heading out as Karolina Muchova won seven games in a row to lead by a set and a break in their semi-final on Arthur Ashe Court.