In the second Battle of the Sexes (1973), Bobby Rigs faced off against Billie Jean King and lost 6-4, 6-3, 6-3 in straight sets. The controversy behind this match, however, is that some feel Riggs intentionally threw the match. It can be noted that he beat Margaret Court months earlier in straight sets and she was the No. 1 ranked woman in the world, and there were a lot of balls Riggs didn't go for. Some blame Riggs' old age for those differences, but others believe he legitimately threw it to help both tennis and women's tennis as a whole.
Verdict: Despite the fact that Riggs was much older, based on everything that's known, it'd be hard for a lot of people to believe he gave his all in the match. As aforementioned, that same year he made quick work of a female tennis player that was considered better, not to mention multiple sources say he didn't go for a lot of balls he could have or would have in other situations.