UNCASVILLE, Conn. — Alyssa Thomas had 17 points, 11 assists and eight rebounds to help the Connecticut Sun stave off elimination and force a decisive Game 5 of the W.N.B.A. Finals with a 90-86 win over the Washington Mystics on Tuesday night.

The title will be decided Thursday night in Washington with a first-time champion crowned. Thomas fell just short of the first triple-double in Finals history.

Jonquel Jones had 18 points and 13 rebounds to lead the Sun.

Connecticut blew a 16-point halftime lead as Washington used a huge third quarter to tie the game at 68. The Mystics kept it going to start the fourth, opening up a five-point lead. With its season on the line, the Sun responded.

Jasmine Thomas hit a 3-pointer to put the Sun ahead by 84-81. The lead was short-lived as Emma Meesseman answered with a 3 from the wing to tie the game again.