Another big-name player is apparently joining the mix of unrestricted free agents this summer.

Milwaukee Bucks All-Star swingman Khris Middleton has reportedly declined his $13 million player option for next season, his agent, Mike Lindeman, told ESPN's Adrian Wojnarowski. The Bucks and Middleton are planning to work toward a new long-term deal as he is expected to command a five-year max contract to stay in Milwaukee. If he opts to sign elsewhere, Middleton would be eligible for a four-year max deal with another NBA team.

Milwaukee Bucks All-Star forward Khris Middleton is declining his $13M player option and will become an unrestricted free agent, his agent, Mike Lindeman of Excel Sports, tells ESPN. Middleton and Bucks are planning to work together toward a new long-term deal, sources said. — Adrian Wojnarowski (@wojespn) June 19, 2019

Middleton is expected to command a five-year max contract to stay with the Bucks – or a four-year, max deal elsewhere in the NBA. https://t.co/JJzxSSyn21 — Adrian Wojnarowski (@wojespn) June 19, 2019

In not opting in with the Bucks, Middleton joins a growing list of new names on the unrestricted free-agent market that includes the Boston Celtics' Al Horford and Kyrie Irving, the Sacramento Kings' Harrison Barnes and the New Orleans Pelicans' Julius Randle.

Middleton averaged 18.3 points, six assists and 4.3 rebounds this season en route to earning his first career All-Star selection. Middleton said at season's end he first will consider what’s best for himself and his family and then consider which team he fits with best.

“It’s going to be fun and a new position,” Middleton said at his exit interview in late May. “I’m excited about the opportunity.”

The Bucks had the best record in the NBA during the regular season and were two wins shy of reaching The Finals. Now, the franchise and its fans must face the reality that the roster -- outside of Eric Bledsoe and superstar Giannis Antetokounmpo -- could look a lot different next season. Milwaukee has starters Malcolm Brogdon (restricted) and Brook Lopez (unrestricted) as well as reserves Tim Frazier (unrestricted) and Nikola Mirotic (unrestricted) as free agents this summer.

The Bucks became just the sixth team in NBA history to win the first two games in either the conference finals or NBA Finals and then drop four straight to lose the series. But Bucks coach Mike Budenholzer, who led Milwaukee to a league-best 60-22 record during the regular season, made quite an impression in his first season.

Information from The Associated Press was used in this report.