Yet not just the removal of Messi at halftime tipped the balance of play more toward the Americans during a second half they refused to buckle despite losing Mastroeni to a second caution in the 71st minute, about 11 minutes after he'd received the first one.
Another second-session sub, Maurice Edu, helped the USA gain control of midfield with his range and passing as it breached the Argentine back line several times.
Freddy Adu replaced Clint Dempsey in the 61st minute and withstood so many challenges he suffered four fouls from the impatient Argentines.
Heath Pearce celebrated his third straight start at left back by defending his corner solidly, pushing forward occasionally, and latching onto a clever Bradley header to fire a shot on goal.
While Argentina -- which on Wednesday beat Mexico, 4-1, in San Diego -- held sway in the first half as Messi prompted and probed, the Americans conjured up chances. A deflected Dempsey shot looped just wide, Pearce's first-time shot forced Roberto Abbondzanieri to save at the near post, and a Dempsey cross fell for Eddie Johnson to head right at the goalie.
Howard, though, must have felt as if the field were slanted steeply in his direction. In just the fifth minute, he stopped Cruz twice in a few seconds by blocking his initial, close-range effort and then swatting aside his follow-up shot from an acute angle. He thwarted Cruz twice more in the second half as Messi toyed with his challengers by slipping into the middle to serve his killer balls after testing both flanks in the early minutes.
The halftime subtraction of Messi and addition of Edu had yet to take effect when Landon Donovan ran at the Argentine defense in the opening seconds and won a corner kick that Donovan, celebrating his 100th cap, curled into the goalmouth and Onyewu headed squarely and powerfully off the crossbar.
The pell-mell start by the Americans brought more fans into the game and forged a raucous atmosphere that crested often during an eventful second half. Cruz's attacking partner for most of the match, Sergio Aguero, ran onto a short Cruz feed and jumped over Howard's dive at the ball that caught some of Arguero - and none of the ball - as the Americans cleared, but referee Joel Aguilar Chicas watched Aguero tumble to the ground and then followed the play back upfield.
Another forward-keeper confrontation at the other end didn't turn out so well for the USA. midway through the second half. Eddie Johnson ran onto a great long ball from DaMarcus Beasley and veered at Abbondanzieri, who came out quickly. In his hesitation Johnson pushed a ball into a clump of players, crashed into the keeper, and needed a few minutes to recover from the collision.
A cracking tackle by Edu earned him a caution in the 70th minute, and shortly thereafter referee Chicas also cautioned Mastroeni, apparently for dissent, and after a few moments brandished the red. Javier Mascherano followed him in the 86th minute after a vicious kick took down Donovan at midfield.
Slipping and skidding had increased as a driving rain fell harder in the second half and the 10-v-10 situation opened up gaps in the final minutes. The USA broke away in stoppage time with a three-on-two and Donovan fed Sacha Kljestan on the right flank; Kljestan cut inside to find some space but a desperation tackle blocked his left-footed shot.
The Americans can count themselves fortunate that Messi played only the first half, and that Donovan's tight groin didn't prevent him from lasting until the final minutes. Yet despite its designation as a friendly, this match featured ample portions of the fight and intensity and bite of the games that do matter.
For the purposes of preparation and precision as well as pride, matter they do, as witnessed by 78,682 fans, a national TV audience, and perhaps tens of millions of disbelieving Argentines.
June 8 in East Rutherford, N.J.
USA -- Howard, Cherundolo, Onyewu (DeMerit, 61), Califf, Pearce (Lewis, 78), Bradley (Edu, 46), Mastroeni, Dempsey (Adu, 61), Donovan, Beasley (Hejduk, 91+), Johnson (Kljestan, 74).
Argentina - Abbondanzieri, Rodriguez, Burdisso (Demichelis, 46), Heinze, Zabaleta (Zanetti, 77), Gago, Rodriguez (Cavenaghi, 74), Mascherano, Cruz (Lopez, 64), Aguero (Banega, 88), Messi (Sosa, 46).
Shots on goal: 4/7
Corner Kicks: 7/6
ARG - Nicolas Burdisso (caution) 18th minute.
USA - Pablo Maestroeni (caution) 60.
USA - Maurice Edu (caution) 70.
USA - Pablo Maestroeni (caution) 71.
USA - Pablo Maestroeni (sent off) 71.
ARG - Gabriel Heinze (caution) 84.
ARG - Lisandro Lopez (caution) 84.
ARG - Javier Mascherano (caution) 86.
ARG - Javier Mascherano (caution) 86.
ARG - Javier Mascherano (sent off) 86.
Referee:Joel Aguilar Chicas (El Salvador)