TOKYO, July 28 (Reuters) - Even without Simone Biles the United States will still offer a steely defence of the Olympic women"s gymnastics all-around crown worn by an American since the 2004 Athens Summer Games. Unbeaten in any all-around competition she entered since 2013, Biles was considered a lock to defend her title until Tuesday when the 24-year-old sent shockwaves through the Tokyo Games after dropping out of the team event following her opening vault. In a stunning admission Biles later explained that the pressure of living up to expectations and her quest for a record gold medal haul had left her no choice but to drop out for her own mental health. USA Gymnastics (USAG) confirmed on Wednesday that Biles would not take part in the all-around but did not rule her returning for next week"s apparatus finals. "After further evaluation, Simone Biles has withdrawn from the final individual all-around competition at the Tokyo Olympics, in order to focus on her mental health," said the USAG. As gymnasts prepared for Thursday"s all-around battle it was left to Sunisa Lee and Biles replacement Jade Carey to defend the title she won at the Rio Olympics. Carey, the next highest ranked American behind Biles and Lee in qualifying, was denied the chance at a medal due to the two athletes per nation quota restrictions placed on the all-around. By no means will Carey be considered a long-shot having placed ninth in Sunday"s qualifying. But the United States best hope of hanging onto the all-around crown for a fifth straight Olympics will likely rest with Lee. The 18-year-old Hmong American flashed her all-around credentials at the U.S. Trials where she outscored Biles on the second day of the two day competition and then underscored that potential in Tokyo placing third in qualifying behind Biles and Brazilian Rebecca Andrade. Russia, competing in Tokyo as representatives of the Russian Olympic Committee (ROC) because the country was stripped of its flag and anthem for doping offences, will be trying to return home with the all-around title for the first time since Tatiana Gutsu of the United Team went atop the podium at the 1992 Barcelona Olympics. The ROC will have two strong medal contenders but European all-around champion Viktoriia Listunova will not be one of them after the 16-year-old fell victim to the two-per country quota rule. Listunova qualified sixth but behind compatriots Angelina Melnikova and Vladislava Urazova, who finished fourth and fifth respectively.