Thai bosses believe the crystals will turn the 90million pounds City of Manchester Stadium into "positive energy and harmony".
"It's really bizarre behaviour," the Mirror quoted a club source, as saying.
Owner Thaksin Shinawatra and executive chairman Garry Cook also attended a crystal-burying ceremony earlier this week.
"They used a special tool and sunk several crystals into the ground beneath the centre circle," the source said.
Mr Cook is also planning to use feng shui all around the 48,000-seat stadium.
Lucky fortune trees, three-legged money toads and buddhas have been put around reception areas, offices and the club shop.
The bosses will also be putting lucky Thai pennies in the club safe.
"The stadium is littered with these bizarre symbols. It's hilarious, one of the fortune trees still has the tag on, it's from B and Q for ?24.95. But if it helps us to win games, then who cares?" said a source.
Feng shui practitioner Simon Brown said the club was right to try to inspire the team.
"Crystals come from deep inside mountains and have a strong energy. Putting them under the pitch will bring that energy on to the field. The three-legged toad and lucky trees are aimed at promoting financial success," he said.