But his Sooners rallied from a six-point halftime deficit and gave him the 69-65 milestone victory over Northwestern State Friday evening at Lloyd Noble Center.
"Coach getting 500 wins is a testament to how hard he's worked and I respect him," said forward Romero Osby, who finished as the only Sooner in double figures with his 11.
In fact, just three players in the game eclipsed the double digit plateau, with Demons guards Jalan West and Shamir Davis netting 13 and 10, respectively.
Both teams had more turnovers than assists and neither hit 40 percent of their field goal attempts.
"We didn't finish some opportunities perhaps," Kruger said. "It didn't seem like early we had much attack on the offensive end."
That led to OU squandering a seven-point first half lead and trailing 32-29 at intermission.
But the Sooners came back and re-seized the lead at 40-38 by the first media timeout of the second frame.
"I thought we started the second half attacking and getting it downhill a little bit and getting to the free throw line, which gave us a little energy early," Kruger said.
Nonetheless, they couldn't ever shake the Demons.
In fact, neither team ever led by more than seven, with each having a six-point edge in the final 20 minutes.
Northwestern State was the latest to do so with 5:35 remaining, but OU closed on a 12-2 run to finish the game.
When the Demons pulled to within one with 28 ticks left, guards Steven Pledger and Je'lon Hornbeak combined for 3-for-4 free throw shooting to put it away.
"We couldn't break out like we really wanted to, but we buckled down at the end of the game," Pledger said.
Because of that, they move to 6-1 on the season with a road trip to Arkansas on the horizon at 6 p.m. Tuesday in Fayetteville, Ark.
After that, it'll be 11 days off before the All-College Classic against Texas A&M and a three-game home stand leading into conference play.