Gym owner Art Ramalho is scheduled to speak at the Friday afternoon rally.
Ramalho helped train Lowell native Micky Ward, whose life story was the inspiration for the film “The Fighter,” starring Boston native Mark Wahlberg.
Ramalho called Warren a “fighter we need in our corner.”
Republican incumbent Scott Brown on Thursday embarked on a campaign bus tour with stops in Milford, North Grafton, Framingham and Wakefield. The tour is scheduled to conclude Monday night in Wrentham, where Brown lives.
Also Friday, Worcester Mayor Joe Petty and five former mayors of the city — including Lt. Gov. Timothy Murray — will formally endorse Warren.
Election Day is Tuesday.