MAR DEL PLATA, Argentina -- Feliciano Lopez upset Juan Martin del Potro 4-6, 7-6 (2), 7-6 (4), 6-3 Friday, allowing Spain to escape the first day of the Davis Cup final tied 1-1 tie with Argentina.
But Lopez took the two tiebreakers, and del Potro injured his right thigh in the sixth game of the fourth set. After treatment, he lost his serve and Lopez cruised to victory in 3 hours, 19 minutes, hushing the boisterous crowd of about 10,000 at Islas Malvinas Stadium.
But the manner of Nalbandian's easy and quick singles win may persuade Argentina captain Alberto Mancini to play Nalbandian in doubles. He has a 7-1 record in Davis Cup doubles, and has won with Acasuso and Calleri.
Del Potro is scheduled to open the reverse singles Sunday against Ferrer, depending on the seriousness of his thigh injury.
Spain was playing without top-ranked Rafael Nadal, who has knee tendinitis. Captain Sanchez Vicario replaced him with 56th-ranked Marcel Granollers. The Davis Cup final has not featured a No. 1 player since Australia's Lleyton Hewitt in 2001.
Nadal was vacationing at an undisclosed location, but kept phoning his countrymen for updates.
"He was calling the people on the bench in between points to find out because they cut the TV signal in the hotel he is staying," Lopez said.
Argentina finished second to the United States in 1981 and to Russia in 2006. It chose the blue indoor hard court for the final, trying to curtail the Spaniards' advantage on clay.
After winning the first set, del Potro couldn't break Lopez again in the second as they headed into a tiebreaker. There, Lopez jumped ahead 4-0 and won 7-2.
There were no breaks either in the third set, in which Lopez won five straight points in the tiebreaker and clinched the set with one of his 17 aces. In the fourth set, Lopez broke del Potro in the fourth game but del Potro came right back with a break of his own.
Del Potro was trying to reach a crosscourt shot on the baseline when he injured himself. He left the court to be attended by doctors but when he returned he was obviously affected by the injury.
Lopez's win bolstered Spain's hopes of winning its third Davis Cup, and first away from home. After Nadal withdrew this month, Spain's chances were diminished considerably, but it promised to fight for every point.
Ferrer, however, was routed by Nalbandian in under two hours. Nalbandian broke Ferrer in the third game and led all the way.
"I played a great match," Nalbandian said after his 17th win in 21 Davis Cup singles. "I couldn't have played it any better. It was good to win it fast."
Ferrer still leads their head-to-heads at 6-4, but all of Nalbandian's wins have been on hard courts.
"No match against David is easy but I didn't have good feelings on the court," Ferrer said.