CIBC, which is sponsoring the Games, says it is offering a 25-per-cent discount on all remaining tickets from 10 a.m. Wednesday to 9 p.m. Thursday.
People buying tickets online can get the discount by using the code CIBCPANAM.
Games organizers said last week that some 650,000 of the 1.4 million tickets available for both events have been sold.
They said Tuesday no updated numbers were available.
The Toronto 2015 organizing committee has said it doesn't expect to sell every ticket.
Note to readers: This is a corrected story. An earlier version incorrectly said that 650,000 tickets had been sold for the Pan Am Games alone.