For the second time this season Clark notched a career-high 32 points, but the Sooners were on the wrong end of a 90-83 loss to visiting Kansas on Wednesday night at Lloyd Noble Center in front of 13,127 fans.
OU trailed for the entire second half and was down by as many as 12 points midway through the half. The Sooners clawed to within four points on several occasions but could not get any closer.
"I thought our guys battled hard," coach Lon Kruger said. "We had a couple of stretches in there where we didn't compete like we have to against a club like that to have a chance that we like to have. We have got to keep learning, keep going, keep working, keep attacking and staying aggressive."
Kansas (10-4, 1-0) was on fire in the first half, shooting 64 percent from the floor. But through it all, OU managed to take a 43-39 lead until the Jayhawks swung the tide of the game with an 11-1 run to close the half and scored the first five points in the second half.
OU (12-3, 1-1) negated a lot of KU's post presence, but freshman guard Wayne Selden set the tone early in scoring 24 points.
Clark was 10-of-18 from the field and 12-of-16 from the free throw line. He also scored 32 points in a loss to Michigan State in November.
"We just have to go back to the drawing board," Clark said. "It all starts on defense. Defense wins games. We just have to come together as a group and figure out what it is we are not doing and get better at it."
Sophomore guard Buddy Hield had 18 points, while senior Tyler Neal added 11 points off the bench. OU couldn't get into a rhythm against the Jayhawks, being outrebounded 36-22 and only having seven assists against nine turnovers.
A lot of the rebound inefficiency was because of foul trouble to Ryan Spangler. OU's primary post presence, Spangler only four points and three rebounds in 23 minutes.
Perry Ellis added 22 points and 11 rebounds for KU. OU is back at Lloyd Noble Center against undefeated Iowa State 11 a.m. CST Saturday.