The main act of pop sensation Taylor Swift's wedding to NFL star Travis Kelce was due to get underway Friday, as celebrities flooded New York for the A-lister extravaganza at the storied Madison Square Garden.

The billionaire singer and three-time Super Bowl champion, both 36, opened the festivities Thursday with an exclusive rehearsal dinner -- only around 100 guests were invited.

Swift, who announced her engagement to Kelce last August, has been tight-lipped about what will surely be the wedding of the year, and guests have reportedly signed non-disclosure agreements.

But all signs point to the celebrations, which fall as Americans mark the 250th US anniversary, being a glitzy affair befitting one of the world's most famous couples.

An AFP journalist saw a procession of black SUVs, believed to be carrying guests, pulling into a privacy tent outside the Garden late Thursday while fans buzzed nearby for a peek at the action.