Germany's Tim Puetz and Jan-Lennard Struff stunned Spain's Marc Lopez and Feliciano Lopez to open up a 2-1 lead in their Davis Cup quarter-final.
The world No. 1 had been inactive since January 23 when he retired with a leg injury from his Australian Open quarterfinal match against Marin Cilic, but showed little signs of rust upon dismantling Philipp Kohlschreiber 6-2 6-2 6-3 to even five-time Davis Cup champion Spain with Germany, 1-1.
Spain's Rafael Nadal celebrates winning his quarterfinal match against Germany's Philipp Kohlschreiber.
"Physically, I have felt good in the last few days and I hope to be well for Friday", said Nadal who has played in four of Spain's Davis Cup winning teams. "So John took a little pressure off of me, which was nice of him, so thanks John", Querrey said during an on-court interview.
Five-time champions Spain, meanwhile, have won 26 straight home ties, with their last defeat on Spanish soil against Brazil in 1999.More news: Pep Guardiola calls for City fans' help in Manchester derby
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Despite the pressure, Nadal can look ahead to his meeting against Zverev with confidence as he boasts a 3-0 record over the beanpole German including their only meeting on clay in Monte Carlo a year ago. "We got a bit lucky but it feels great".
Holder France was tied 1-1 with Italy in Genoa, and 2005 victor Croatia was also deadlocked against visitor Kazakhstan after a day of thrilling action on indoor red clay in Varazdin.
Italy's Fabio Fognini leveled the tie for the hosts after a dramatic four set win over France's Jeremy Chardy.
Croatia took the lead against Kazakhstan when world number three Marin Cilic beat Dmitry Popko 6-2, 6-1, 6-2, before Mikhail Kukushkin levelled the tie after a 3-6, 7-6, 6-4, 6-2 victory over Borna Coric.
The United States could become the first team to seal their place in the semis later yesterday if Jack Sock and Ryan Harrison beat Belgians Sander Gille and Joran Vliegen in Nashville.