Japan's biggest bank, Tokyo Mitsubishi UFJ, is poised to bid for a "substantial" stake in Lehman Brothers (LEH), and may even seek control of the Wall Street investment bank, The Times of London reported Wednesday on its Web site, citing banking industry sources in Tokyo. According to sources close to Tokyo Mitsubishi, the Japanese bank is treating the possible acquisition as a "once in a lifetime" opportunity but it is expected to approach the deal with extreme caution, the newspaper said. However, Tokyo Mitsubishi is not expected to make a concrete offer until after Lehman announces its quarterly results next week which could mark another drop in its share prices, according to the article.