Juan Martin del Potro beat Andy Murray in a thrilling five-hour contest to give Argentina the lead against Great Britain in their Davis Cup semi-final.
Del Potro won 6-4 5-7 6-7 (5-7) 6-3 6-4 after five hours and seven minutes to put Argentina 1-0 up in Glasgow.
The 27-year-old former US Open champion becomes only the third man to beat Murray in a Davis Cup singles match.
British number two Kyle Edmund takes on Argentine number one Guido Pella in Friday's second singles match.
The winners of the best-of-five tie will face France or Croatia in the final.