She made 6 of 8 field goals, including a pair of three-pointers, and was one of few offensive standouts on either side.
Ohio State never led, falling behind by as many as six in the first half when they allowed their hosts to make 12 of 25 field goals (48 percent) to establish a 29-25 lead at halftime.
In the second half, the Buckeyes tied the score twice, at 32 with 15:09 to play and at 36 a minute and a half later, but could never get over the hump.
During that more than five-minutes span, the Buckeyes missed all eight of their field goal attempts and committed three turnovers.
They stayed in the game by holding the Spartans to just three points during the same span, but MSU's Lauren Aitch made a jumper with 3:30 to play and put her team ahead five, 49-44.
With the Buckeyes' offense continually misfiring, that may as well have been 50.
Lykendra Johnson, who scored 10 points in the first half for the hosts, set the final margin with a free throw with 11 seconds left.
Johnson finished with 14 points and 11 rebounds. She made 6 of 9 shots from the field.
Lavender was Ohio State's leading scorer and the only Buckeye to reach double figures. She scored 19 points but needed 20 field goal attempts (8 makes) to do so.
"I think we basically just got outplayed," she said. "Michigan State came out and played extremely hard and we did not match their intensity out there and we ended up on the short end."
As a team, Ohio State shot 20 for 57 (35.1 percent) from the floor, including 1 of 14 from beyond the three-point line.
The Spartans played their first game without staring point guard Brittney Thomas, who blew out her left knee Friday.
Without her, they struggled to handle the ball but were able to manufacture enough offense to come up with the win in front of 10,403 fans at the Breslin Center.
They turned the ball over 20 times and shot 42 percent from the field (21 for 50), leaving Ohio State head coach Jim Foster to call into question his team's offensive execution.
"We did not do a good job of reversing the ball, and started the game taking our shots too quickly," he said. "Based on what they were going through, we knew they were going to struggle getting the ball up the floor letting us get some opportunities early, but as the game progressed they got a little more confident in that area."
Where the defense faltered was on possessions in which not every defender maintained the pressure his team is accustomed to throwing at opponents.
"We had three or four people doing their job when it came to defending, but then the fifth person would let the ball come up without the right kind of pressure we needed to put on them," he said. "That hurt us along with us being in a quick shot mood, and not taking advantage of the things that make us a good basketball team.
"They did a great job and I don't think we did a very good job."
The Spartans moved within a half-game of first place.
The Buckeyes next head to Iowa for an 8 p.m. contest Thursday. That will be the second of a five-game stretch that includes just one home contest.