Back in the Copa America after 12 years, USA could only watch the two-time world champions fly by in the second half.

Eddie Johnson put the US ahead with a penalty kick in the ninth minute, but Crespo scored in the 11th and 64th minutes for fifth-ranked Argentina, who increasingly outplayed the Americans as the game progressed.

Aimar connected in the 78th minute and Tevez scored in the 85th, six minutes after entering.

"We came down here to win. We didn't come here to walk around with our tail between our legs and hope for the best," said defender Jimmy Conrad, one of the few regulars to play for the Americans.

"Ultimately, win or lose, it's a great learning experience for our team, and I think our programme will become better because of it."

With Diego Maradona looking on in a national team jersey, Crespo raised his national team goals total to 34, matching the former captain's career total.

"For me it's a great honour to equal the number of goals by Diego," Crespo said.

The loss was the first for the United States since a 2-1 defeat to Ghana on June 22 last year in Germany, which eliminated the Americans from the World Cup. They had been 10-0-1 under Bob Bradley, who coached his first road game since replacing Bruce Arena as coach late last year.

"We put a lot of effort into the first 60 minutes, and I think when Argentina raised the level over the last 30 minutes, we weren't able to match that," Bradley said.

Kasey Keller made his 101st international appearance, moving ahead of Tony Meola for the record among US goalkeepers, but he was overwhelmed in the second half as his defence tired.

"At times, we didn't do a good enough job holding the ball," Bradley said. "We just started trying to beat their defence with one pass, and I think we needed to be able to move better off the ball and keep possession a little better."

The United States shocked Argentina 3-0 in the first round of the 1995 Copa America in Uruguay, but the Albiceleste already were assured of advancing and left many regulars out of their starting lineup. This time, Argentina fielded a full-strength lineup filled with stars from the world's top clubs.

Defender Jonathan Bornstein and midfielder Benny Feilhaber were the only holdovers from the US starting lineup Sunday, when the Americans beat Mexico 2-1 in Chicago to win their second straight CONCACAF Gold Cup.

Instead, the 13th-ranked Americans fielded a youthful side that included six starters with 10 international appearances or fewer and debutants Marvell Wynne and Herculez Gomez.

Feilhaber, who had a spectacular winning goal against Mexico, created the play that led to the penalty. He split the defence with a pass half the length of the field and Johnson ran onto the ball for a breakaway when he was tripped from behind by Gabriel Milito.

Johnson slotted the ball to his right post, with goalkeeper Roberto Abbondanzieri going the other way, for his 11th goal in 27 international appearances.

Argentina did not waste any time in getting the equaliser. Juan Roman Riquelme took a freekick from about 35 yards out. The ball bounced through the defence and Gabriel Heinze got to it ahead of Keller. The ball went to Crespo, who put it in the open net.

Keller leaped in the 43rd minute to prevent a goal, using his right hand to tip Juan Sebastian Veron's blistering right-footed shot from about 30 yards off the crossbar.

Crespo scored his second goal off a pass from Lionel Messi, speeding unmarked into the penalty area and beating Keller from eight yards.

Aimar scored on a header from 12 yards off a cross from Heinze, who bent the ball back from near the corner.

Tevez then collected a through ball from Riquelme on a failed offside trap, touched it ahead to himself and slotted the ball just inside the post to Keller's right.

Next Monday, USA play Paraguay while Colombia face Argentina.