Mar Del Plata, Argentina ? Venezuelan leader Hugo Chavez, emboldened by thousands of anti-American protesters, is getting a rare chance to stand up to his adversary, George Bush, with promises to keep the president from reviving talks on a free trade area stretching from Alaska to Argentina.

The two men arrived in Argentina for the fourth Summit of the Americas on Thursday, the same day Venezuela staged a mock U.S. invasion of its own territory. The event is the latest exercise intended to prepare soldiers and civilian volunteers for what Chavez says is a possible attack by American troops.

U.S. officials deny any such plan, but Chavez says it’s best to be ready – just in case.

With tensions rising between the two nations, Chavez and Bush will likely see each other today at the summit’s inauguration – after Chavez addresses a rally of mostly anti-Bush protesters. The two leaders are not scheduled to meet one-on-one, but they will both be taking part in the same summit sessions.

Chavez has joked about whether Bush is afraid of him, saying he might sneak up and scare Bush at the summit.

President George Bush and first lady Laura Bush arrive Thursday at the international airport in Argentina's Atlantic coast resort of Mar del Plata to attend the Summit of the Americas. They are greeted by U.S. Ambassador to Argentina Lino Gutierrez, left.

Bush has brushed aside Chavez’s attempts to turn the summit into a showdown, saying he is focused on announcing job creation programs and promoting free trade in the region.

“The purpose of the summit is for the democratically elected leaders to get together and reaffirm the fact that there is really a shared vision for the hemisphere,” National Security Adviser Stephen Hadley said in a pre-summit briefing in Washington.