"I'm happy to win, but a bit disappointed with the performance," said O'Connell after the Lions were made to work hard to claim their third successive tour victory.
"We started very well and played some good stuff, but then we went to sleep. They competed well at the breakdown and got a lot of turn overs.
"Poor discipline let them back into the game and they scored some good tries."
The Lions built a 20-0 lead inside the opening quarter before the Cheetahs claimed two tries of their own while Lions try scorer Stephen Ferris was in the sin between the 23rd and 33rd minutes.
O'Connell's men relied heavily on the boot of James Hook as he kicked four penalties and two conversions to finish with a 100-per-cent record, while the Cheetahs were left to rue missed attempts from fly-half Jacques-Louis Potgieter and replacement Louis Strydom.
In the end, only a missed drop goal from Strydom ensured the Lions kept up their winning start to the tour, but O'Connell did point out that maintaining that winning momentum was particularly important.
"There were nine guys making their first start in our team and this now means everyone has had a game," added O'Connell.
"But a win is a win and we move on from here."