Boston Celtics star Gordon Hayward has reportedly opted out of his contract and is set to enter NBA free agency.

Hayward was due to earn $34.2million in 2020-21, but the Celtics forward is now set to become one of the top players on the free agent market, according to ESPN.

The 2017 All-Star could still re-sign with the Celtics on a long-term deal, though the New York Knicks and Atlanta Hawks have significant cap space to lure Hayward.

Hayward left the Utah Jazz for the Celtics on a four-year max contract via free agency in 2017, but he has endured a difficult time in Boston.

The ninth pick in the 2010 NBA Draft, Hayward suffered a gruesome fractured tibia and dislocated ankle in his first game for the Celtics three years ago.

Hayward struggled to recapture his best form the following season, and the 30-year-old sustained a broken bone in his hand in November before suffering a sprained right ankle during Boston's sweep of the Philadelphia 76ers in the opening round of last season's playoffs in Orlando.

He did not return until midway through the Eastern Conference finals against the Miami Heat.

Hayward averaged 17.5 points, 6.7 rebounds and 4.1 assists per game for the Celtics last season, having averaged 11.5 points, 4.5 rebounds and 3.4 assists in 2018-19.

Since entering the league, Hayward is averaging 15.3 points, 4.4 rebounds and 3.5 assists per game.