The hockey player is thought to have celebrated his last few days as an unmarried man in LA club Trousdale on Tuesday.
An insider told the New York Post: "He was with seven friends, and they sat in a VIP booth drinking vodka. They had a great time, but Mike was pretty well behaved."
However, Duff has apparently avoided going out and has been exercising regularly to prepare for their ceremony.
The pair will allegedly marry this week.