Williams hit a key 3-pointer as the shot clock expired with 1:27 left to up Tulsa's lead to 73-66 and, on the next possession, the Sparks had a 3-pointer waved off because of a shot-clock violation.
Courtney Paris had her sixth double-double of the season with 12 points and 13 rebounds and Karima Christmas had 11 points as the Shock (14-14) won their ninth home game of the season, the most since moving from Detroit in 2010. They are one win or a Seattle loss from their first playoff appearance in Tulsa.
Candace Parker had her seventh straight double-double with 24 points and 11 rebounds. She had 19 points in the second half to help the Sparks (11-18) battle back from a 15-point deficit.