>> reporter: she responded in a flash, leaping forward to protect her husband from an attacker. instinctive, fierce, athletic. a former volleyball player in school. all that, plus a lot more. the young, glamorous, chinese-born third wife of rupert murdoch.
>> i think all the people are movers and shakers here.
>> reporter: for hours, all through her husband's grueling testimony today, wendy murdoch was right behind him, willing him on, clearly ready to respond.
>> watching him so carefully, she was the first to be able to get up and, before the police or before anyone else, swat away this aggressor.
>> reporter: now, 42, wendy murdoch has been married to the 80-year-old media baron for 12 years since meeting him as a young executive for one of his tv operations in hong kong. the union was controversial at first. rupert murdoch now 102-year-old mother called her new daughter-in-law a designing woman, especially after she challenged her husband's adult children, fighting for their two young daughters to get a stake in the company. murdoch with charlie rose.
>> we try to combine the best of chinese and best of american method to teach them.
>> reporter: and her history, coming to the u.s. on a student visa and then marries her first husband, a man with his then-wife had sponsored her. as first reported in the " wall street journal."
>> what ended up happening is wendy, who was a teenager at the time, had an affair with the father of her sort of adopted father. and the two of them ended up getting married for long enough for her to get a green card.
>> reporter: now wendy is widely viewed as an important asset to murdoch. helping represent his business interests in china and easing his way through social and charitable circles.
>> this is someone what was the daughter of someone that ran a factory in china and made it to yale and a successful business career as well as this very high-profile marriage.
>> reporter: those that know wendy murdoch say she's unstoppable. whatever happens to her husband she and her children will have a secure future. brian?
>> andrea mitchell rounding out our coverage. thanks.