Gisele Bündchen ''illuminates'' Tom Brady's day.

The American football quarterback paid a sweet tribute to his model spouse with an adorable post on Instagram to mark her 39th birthday.

Sharing a sweet photo of his wife alongside two heart emojis, Tom captioned it: ''Happy Birthday Mamai! You are the light that illuminates our days!!!! We love you so much!! (sic)''

Meanwhile, the 41-year-old sportsman - who has Vivian, six, and Benjamin, nine, with his wife - previously insisted couldn't wish for a ''better partner for him in his life'' than his wife Gisele after they met ''under pretty trying circumstances'' back in 2006.

Tom had only been dating the supermodel for a matter of weeks when he found out that his ex-girlfriend Bridget Moynahan - whom he dated for two years - was more than three months' pregnant with their son John, now 10, but she agreed to stick by him.

Tom said of his wife: ''She had five sisters and I had three sisters, so it's a lot of women. And, you know, she comes from a different country and to move to New York when she was 17 and we met each other under pretty trying circumstances. And I think in a lot of ways that really challenging experience brought us together, in a very tight way.''

Asked how being with Gisele has enhanced his life, he added: ''Oh man, every possible way, it really has. I couldn't imagine a better partner for me in my life, what I've gone through, how she supports me, the mom she is to our kids.''