Developers have reduced the size of an office building in an upcoming phase of the $500 million Boston Landing development in Brighton.

The plans now call for a 99-foot-tall, 135,000-square-foot office building, down from a 165-foot, 225,000-square-foot building that was approved in 2014 for the 1.3-acre parcel at 40 Guest St.

The 4-story building would still include accommodations for a professional sports team, according to documents submitted last week to the Boston Redevelopment Authority.

The top two floors would contain offices and athlete training areas including locker rooms, basketball uses, studio production and “other uses typical of a professional sports organization and their guests” including seating for up to 195 spectators, according to a letter by attorney Lawrence Kaplan of Goodwin Procter, representing New Balance subsidiary NB Development.

The lower two floors would contain office and lab space. Plans also call for a 7,000-square-foot restaurant.

The Boston Celtics currently practice at The Sports Authority Training Center at Healthpoint, a complex connected to Boston Sports Club in Waltham. Celtics spokesman Chris Megliola did not respond to requests for comment.

NB Development submitted a notice of project change to the Boston Redevelopment Authority last week, updating the master development plan approved in 2014. NB Development spokeswoman Mary Lawton declined to comment on the reason for the proposed changes.

Details about another building at 60 Guest St. will be described in a future filing, according to the Kaplan letter.

The 1.8-million-square-foot, $500 million Boston Landing development is anchored by the new 250,000-square-foot headquarters for New Balance, which opened in 2015. NB is partnering with Boston-based HYM Investment Group on a 10-story, 190,000-square-foot spec office building under construction at 80 Guest St and 295-unit apartment complex at 125 Guest St.

Construction of the 175,000-square-foot Warrior Ice Arena at Boston Landing, which will become the new training facility of the Boston Bruins, is scheduled to be completed in September.

Other previously-approved elements of the project include 80,000 square feet of retail and restaurant space and a 175-room hotel.

And the old 228,901-square-foot New Balance headquarters at 20 Guest St. is being renovated to provide new offices for Harvard Business Publishing as it relocates from 300 North Beacon St. in Watertown.