Uruguay's Pablo Cuevas becomes his nation's first Top 20 player thanks to his final in Hamburg.
Andy Murray has announced his withdrawal from next week's Rogers Cup.
Croatian pair top Bryan Brothers to cut USA lead to 2-1.
Del Potro, Pella edge Italians Fognini, Lorenzi giving Argentina 2-1 lead.
In all-American clash, Young surges into first semifinal since 2015.
World No. 5 Simona Halep is the latest to announce her Rio withdrawal.
Two seeds fail to survive Hamburg quarterfinals, Renzo Olivo survived near facial trauma.
