SOFIA, Bulgaria (AP) - Tocarra Montgomery of the United States won her first two matches by pins Thursday, putting her in good position to advance to the second round of wrestling's world championships.     Montgomery is competing in the 1491/2-pound division of a tournament that had been scheduled for Sept. 26-29 in New York. The championships were postponed because of the terrorist attacks and shifted to Sofia.     Among the U.S. men, Stephan Abas defeated Kripa Shankar of India 8-1 at 119 pounds but lost 7-6 to Herman Kontoyev of Belarus.     Joe Williams, trying to improve on his fourth-place finish at the 1999 world championships, downed Canada's Nick Ugolaha 4-3 in overtime at 1671/2 pounds.     At 2133/4 pounds, Dominic Black defeated Gankhuyag Ganzoreg of Mongolia 11-7 points but lost 6-2 to Vadim Tasoev of Ukraine.     Germany's Alexander Leipold, the Olympic champion stripped of his gold medal after failing his post-Olympic drug test, defeated Ukraine's Volodymyr Sirotyn 5-3 at 1671/2 pounds.     Leipold was banned from competition for one year and was not scheduled to wrestle in New York. However, his one-year ban has since expired, making him eligible for Bulgaria.