The Sky's losing streak hit nine with a painful overtime loss on Friday against the WNBA's worst team.
Host Tulsa (4-18) rallied from an eight-point fourth quarter deficit to force a 70-70 deadlock by the end of regulation and prevailed 81-78 in overtime at the BOK Center.
Now 8-14, the Sky have dropped 13 of their last 14 games mid-June. Tulsa, which entered the game with the WNBA's poorest record, snapped a five-game losing streak.
Sky guard Courtney Vandersloot hit a 3-point field goal with 1:09 left in overtime to cut the Shock led to 79-78, but Riquna Williams replied with a jumper with 46.4 seconds left for a three-point lead.
Potential game-tying 3 point tries by Epiphanny Prince and Shay Murphy in the final 6.8 seconds missed.
Chicago saw a late eight-point fourth quarter lead vanish as Tulsa forced a 70-70 tie by the end of regulation and a five-minute extra session.
Williams and Roneeka Hodges each had 22 points while Jennifer Lacy had 15 points off the bench for Tulsa.
Vandersloot scored a career-high 23 points, Murphy had 17 and Swin Cash and Prince each had 11 for the Sky.
The Sky opened a 36-33 lead by halftime as stiff defense held the Shock to just 34.4 percent shooting.
Sky guards provided a first half lift with 28 points, including eight from Murphy in her first Sky start while Vandersloot had 12 off the bench.
The Shock crept to within one point at 44-43 on a Hodges 3 pointer with 4:40 left in the third but never overtook the Sky, who led 53-47 entering the fourth quarter.
Tulsa then rallied from a 70-62 deficit in the final 2:14 and tied the game after a Johnson steal and Vandersloot foul on Hodges, who hit two free throws to force a 70-70 tie with 9.3 seconds left in regulation.
Prince's three-point try with 0.2 showing missed and sent the game into overtime.
Chicago travels to Connecticut on Sunday, then hosts the Sun on Tuesday. Tulsa is at San Antonio on Saturday and at Atlanta on Tuesday.