Alyssa Thomas' 2021 WNBA season may be in jeopardy after she underwent successful surgery on Tuesday afternoon to repair a torn Achilles tendon.

Sources say that Thomas, an unrestricted free agent who has played seven seasons with the Connecticut Sun, suffered the injury during a Jan. 12 practice with ZVVZ USK Praha of the Czech Republic.

No timetable has been set for Thomas' return but the injury is among the most devastating for an athlete.

Seattle Storm star Breanna Stewart tore her Achilles while playing for Russia's Dynamo Kursk in April 2019. She missed all of that WNBA season. She returned in 2020 and helped Seattle to its second WNBA championship in three seasons and its fourth overall.

Las Vegas Aces point guard Kelsey Plum tore her Achilles last June and didn't play in 2020.

Thomas' reparative surgery was performed by Dr. Robert Anderson of Bellin Health Titletown Sports Medicine and Orthopedics in Green Bay, Wisconsin. Dr. Anderson also serves as an Associate Team Physician for the Green Bay Packers. He has worked with the likes of Golden State guard Steph Curry, former New York Yankees shortstop Derek Jeter and Richard Sherman, the latter who ruptured his Achilles tendon during a Nov. 10, 2017 game playing for the Seattle Seahawks.

Thomas, a 6-foot-2 forward, had one of the best years of her seven-year career during the abbreviated 2020 WNBA season as she finished in the top 20 in points (15.5 ppg, 16th overall), rebounding (9.0 rpg, third), assists (4.8 apg, seventh) and steals (2.0 spg, first). Stewart was the only other player to finish in the top 20 those same categories.

Thomas helped Connecticut rally from its worst start in franchise history (0-5) and become the third team in WNBA history to lose their first five games and make the playoffs, and the first to reach the semifinals. She also had one of the single-greatest games in Sun history during Game 3 of the 2020 WNBA semifinals (Sept. 24, 2020). She scored eight of her game-high 23 points with a little over three minutes left with 12 rebounds, four assists and a game-high three steals during a 77-68 win over the Las Vegas Aces, two days after dislocating her right shoulder.

The injury is doubly problematic for the Sun. Thomas has been arguably their most invaluable player because of her toughness and unique skills. Their offense is often at its best when she grabs the defensive rebound and pushes the ball up the floor to lead the break and facilitate the offense.

Thomas is also an unrestricted free agent and re-signing her was a top priority. The league doesn't have an injured reserve, so if the Sun re-signed her, paid her for 2021 and she couldn't play, she'd count against both their salary cap and 12-woman roster. Seattle, in 2019, put Stewart on the suspended list for both those reasons. The Sun did the same when they re-signed then-Sun post Chiney Ogwumike to an extension during the 2017 offseason but put her on the suspended list that season because of an Achilles injury.

Oddly enough, Ogwumike's injury led to Thomas finding her perfect niche in 2017 as a facilitating power forward because she moved from small forward to Ogwumike's spot.

n.griffen@theday.com