The Boston Celtics suddenly have an open roster spot after trading Isaiah Thomas, Jae Crowder and Ante Zizic to the Cleveland Cavaliers.

If Boston keeps their team as it is, they can add an available free agent. Here are some free-agent candidates who could join the Celtics for the upcoming season.

Gerald Green

Cs have at least one open roster spot now. Barring another trade, my first call would be to Gerald Green. Huge locker room presence. — Adam Himmelsbach (@AdamHimmelsbach) August 23, 2017

Why He Works — He played for the Celtics last season and was drafted by the team as a rookie.

Age — 31

Minimum Salary — $2.11 million

Tony Allen

FWIW, Celtics are over the cap, so would only have veteran's minimum to spend on free agents. One name that intrigues me: Tony Allen. — Brian Robb (@BrianTRobb) August 23, 2017

Why He Works — Earlier this week, Haley O’Shaughnessy included Allen as one of the top available free agents

“Allen is a six-time All-Defensive Team selection. He’s a lockdown technician, Kobe Bryant’s least-favorite guard to square up against, the Grindfather, a Memphis institution, and a free agent … Allen can still work his skills into the demand-heavy, low-supply market that is NBA defense.”

Age — 35

Minumum Salary — $2.32 million

Shabazz Muhammad

Why He Works — The Minnesota Timberwolves recently renounced his rights, making him an unrestricted free agent. He could be interested in joining a contender and making his postseason debut.

Age — 24

Minimum Salary — $1.57 million