"The better team won," Neil Lennon told Sky Sports following Rangers victory over Celtic in the final Old Firm game of the season on Sunday afternoon.
Rangers won the game 2-0 at Ibrox through goals for James Tavernier and Scott Arfield.
"We lacked energy and we looked tired today," said the Celtic manager.
"I don't know if it's mental or physical fatigue. We got beaten and deservedly so."
Lennon laid blame for the defeat with the players.
"I've told the boys what's expected of them. We were looking for a reaction, even at half-time, and we didn't get one.
"They've got to have a look at themselves today and decide that performance is unacceptable. Even though they've been brilliant for a long period of time.
"Rangers wanted it more today than we did and that's the biggest criticism you can aim at the players.
"We've got a good group and they just let themselves down today.
"I'm disappointed with the quality of play, I'm disappointed with the tempo, disappointed with a lot of aspects of the game today.
"You've got to give credit to Rangers. The game today seemed to mean more to them than it did to us."
💬 REACTION 💬
"That performance was unacceptable"
Neil Lennon was disappointed in his @CelticFC side's 'quality & tempo' in their defeat at Ibrox today.
Watch our full interview below https://t.co/DoCX7RnQRO
— Sky Sports Scotland (@ScotlandSky) May 12, 2019