World number one Novak Djokovic overcame an early ankle injury to lift Serbia to a Davis Cup quarter-finals victory over the United States with a comprehensive 7-5 6-7 6-1 6-0 victory over Sam Querrey on Sunday.
"It's very strong emotion when you play for your country. I guess that's the biggest reason why I kept playing," Djokovic told reporters. "It meant a lot to me personally and the whole team and the nation, and we are very glad to be in semi-finals again."
Serbia won the tie 3-1, with Djokovic grabbing two of those victories.