Juan Martin del Potro fought off stomach problems and beat Ivo Karlovic on Friday, leaving Argentina tied with Croatia in the Davis Cup quarterfinals.
Del Potro defeated Karlovic 6-2, 7-6 (7), 6-1.
Marin Cilic gave Croatia the lead, beating David Nalbandian 5-7, 6-4, 4-6, 7-6 (2), 6-3 in a match that lasted 5 hours, 9 minutes and put pressure on Del Potro.
Nalbandian and Eduardo Schwank are scheduled to face against Cilic and Lovro Zovko in Saturday's doubles match on the outdoor clay court. Nalbandian said he intended to play despite speculation captain Martin Jaite might replace him with Juan Monaco. Reverse singles are Sunday.
The 23-year-old Cilic wore down the 30-year-old Argentine, finally winning on his third match point.