Tayler Hill made two free throws for Ohio State to tie the game at 63 when the teams returned from the last media timeout of the game. Then the Fighting Illini took over, scoring 16 points in the last 3:59 to wrest control of a contest that had featured back-and-forth action throughout.
Karisma Penn, a senior forward from Shaker Heights, Ohio, was the star of the afternoon for Illinois. She notched her eighth double-double of the season with 34 points and 12 rebounds.
Ten of Penn's points came in the final four minutes, when she also had three of her six offensive rebounds.
Illinois guard Adrienne GodBold broke the 63-all tie by making the first of two free throw attempts. The second bounced off the rim but was corralled by Penn, who missed a put-back attempt by was fouled by Ohio State's Darryce Moore. Penn made both ensuing free throws to push the Fighting Illini into a three-point lead with 3:43 to go.
Moore got two of those back with a pair of free throws at the other end, but Penn struck with another basket off an offensive rebound on the following Illinois possession.
Moore scored again thanks to a pretty pass from Raven Ferguson, and Ohio State had a chance to go back in front after Ferguson drew a charge on Illinois guard Alexis Smith with 2:31 to go.
That potential turning point would end up going against the Buckeyes, however, as Moore missed a driving layup then picked up her fifth foul on the other end when Penn drove at her near the basket. Moore compounded matters by slamming the ball off the floor in frustration. It bounced high above the basket as Moore was whistled for a technical foul.
Amber Moore made one of two technical free throws then Penn made a pair resulting from the original foul, putting the Illini up four with two minutes to go.
Ohio State freshman Cait Craft, playing for injured senior Amber Stokes, missed an open three-pointer, and Penn snatched the rebound then added another layup at the other end to make it a six-point game with 1:21 left.
That put Ohio State into desperation mode. Though Hill and Maleeka Kynard both made three-pointers for the Buckeyes in the final 1:04, Illinois could not be denied.
Penn scored off yet another offensive rebound following Hill's three, and Moore made 4 of 4 free-throw attempts in the final 23 seconds to ice the game for the Illini in front of a crowd of 4,516 at Value City Arena.
Illinois improved to 8-6 overall and 1-1 in the conference while Ohio State slipped to 10-5 overall and 0-2 in Big Ten play.
Hill led Ohio State with 30 points while hitting 8 of 17 shots from the field, including 5 of 11 three-point attempts. She was 9 for 11 from the free-throw line and had five rebounds and five assists while playing the full 40 minutes.
Moore had a career-high 17 points on 6-for-8 shooting before fouling out. The reserve post player also had six rebounds and two of Ohio State's 22 assists on 25 field goals.
Center Ashley Adams added 11 points and one rebound while going 5 for 5 from the floor. She was 1 for 5 from the free-throw line, contributing to an overall lacking effort by the team.
The Buckeyes went 16 for 25 (64 percent) from the charity stripe while Illinois was 30 for 34. That included a 16-for-17 night at the line by Penn, the reigning Big Ten and USBWA player of the week.
Ohio State played the second half without Stokes, who went down under the Ohio State basket while trying to make a back-court steal in the final seconds of the first half. The 2012 Big Ten Defensive Player of the Year had her left leg give out while trying to lunge left with her momentum going to her right. After being attended to for several minutes, she was carried off the floor by two members of the Ohio State training staff.
Ohio State head coach Jim Foster called it, "at the very least, a sprain. I wouldn't think we're seeing her for a little bit, but we'll know more tomorrow."
Craft, a freshman from Findlay (Ohio) Liberty-Benton, and Ferguson, a sophomore from Columbus, picked up most of the minutes Stokes would have played in the second half.
Ferguson had eight points and five rebounds but missed 10 of her 13 field goal attempts, including a 1-for-6 showing from beyond the arc.
Stokes' injury came at the end of a physical first half in which only 11 total fouls were called.
The second half was much different as the three-person officiating crew called 32 fouls and sent the teams to the charity stripe a combined 48 times.
Hill did not think the change in the way the game was officiated benefitted either team. She was more concerned with the effort and drive of the Buckeyes.
"I think (Illinois) just wanted it more," Hill said. "They outworked us. We made simple mistakes like not boxing out at the free-throw line. But that's determination."
Ohio State's home winning streak was a school record and the second-longest in the nation behind Baylor.
The Buckeyes lost their Big Ten home opener for the first time in Foster's 11 seasons as head coach, and they fell to Illinois in Columbus for the first time since 2001.