The 22-year-old actress scooped the Best Actress gong at the Academy Awards on Sunday (24.02.13) and was left blushing when Jack, 75, compared her to a former girlfriend and told her he would be ''waiting'' for.
During Jennifer's interview with 'Good Morning America', Jack interrupted and told her ''You look like an old girlfriend of mine'', to which she jokingly responded: ''Oh really, do I look like a new girlfriend?''
However, she was left uncomfortable when Jack replied: ''I thought about it'' before adding ''I'll be waiting''.
It was an eventful night for 'Silver Linings Playbook' star Jennifer - who was previously nominated in the same category two years ago for her role in 'Winter's Bone' - as she received a standing ovation after she stumbled on the stairs leading up to the stage to collect her statue.
Dressed in a stunning Dior Haute Couture gown, she said: ''Thank you so much. This is nuts.
''You guys are only standing up because I fell and you feel bad.''
The blonde beauty, who was accompanied at the ceremony by her parents, also thanked her co-stars, crew and team for their support before wishing her fellow nominee, 'Amour' star Emmanuelle Riva a happy 86th birthday.
Jennifer beat off stiff competition from Jessica Chastain in 'Zero Dark Thirty', Quvenzhane Wallis in 'Beasts of the Southern Wild, Naomi Watts in 'The Impossible' and Emmanuelle, to take home the award.