Novak Djokovic spearheaded Serbia's Sydney triumph as they saw off Rafael Nadal and Spain in the final of the inaugural ATP Cup team event.
Rafael Nadal helped hosts Spain see off Argentina in a deciding doubles contest, setting up a semi-final against Great Britain.
Serbia had hoped to mark Janko Tipsarevic's farewell by winning the Davis Cup, but Russia ruined those plans in Madrid on Friday.
John Isner outlasted Polish opponent Kamil Majchrzak 6-4 6-7 (5-7) 6-3 to book a spot in the last eight at Newport.
Illness forced 2018 champion Damir Dzumhur out of the Antalya Open, while two-time runner-up Adrian Mannarino was beaten in three sets.
There were plenty of shocks at the Nature Valley International, with top seed Guido Pella among several favourites knocked out.
Joao Sousa slipped out of the Antalya Open after a 6-4 7-6 (13-11) defeat to Lorenzo Sonego, as Viktor Troicki scraped into the main draw.
Despite being a set and a break down to Bradley Klahn in Chengdu, Bernard Tomic recorded his first tour-level win since Wimbledon.