SC outscored United Kingdom 33-11 the final 11 minutes, 20 seconds to win 76-68.
The long-awaited debut of Jarred Vanderbilt occurred with 13:09 in the first half. He finished with six points and five rebounds.
Kevin Knox led the Wildcats with 21 points, followed by Richards with 12 and PJ Washington with 10.
Chris Silva paced SC (12-6, 3-3) with 27 points, followed by Frank Booker with 18 and Make Kotsar with 12.
This story will be updated at a later time.
The Wildcats hit one 3-pointer for just the seventh time in the John Calipari era and first since only knocking down one at Vanderbilt on January 10, 2017.
Calipari said United Kingdom played "a lot of the game (without a point guard) and when we did he was not very good".
Kentucky starts a two-game home stand against Florida on Saturday. It wasn't meant to be, but Vanderbilt still gave fans a reason to be optimistic for the remainder of the season.
The Cats' Wenyen Gabriel fouled out with just over seven minutes to play and UK's final bucket of the night came with 6:12 remaining. But that's when SC, fueled by the powerful, 6-foot-9 Silva, got going and outscored Kentucky (14-4, 4-2) 36-14 the rest of the way to pull off the upset. However, the Gamecocks then missed 15 shots in a row and went 10 minutes without a field goal.
SC cut the Cats' lead to 4 with just over 7:00 left before Knox drilled the Wildcats' first three-pointer of the night. SC answered with a 7-0 run to get it to 57-50.
United Kingdom took its largest lead of the game at 57-43 with 11:43 left, but that's where the game turned.
Kentucky's 32 personal fouls are the second most of the Calipari era.
Recipe for a ugly loss to a ranked team, right?
The junior set game-highs in free throws made (nine) and attempted (13). On Monday night, we saw bluebloods Duke and Kansas roar back from double-digit second-half deficits to steal victories on the road against quality teams (Duke over Miami, Kansas over West Virginia).
What irritated him even more was UK's foul trouble.
United Kingdom shot 44.9 percent from the field, making 22 of 49 shots.
But after shooting better than 50 percent to build that 14-point lead, they made just 3 of 14 shots the rest of the way and did not make a single field goal over the final 6:12. Kentucky was outrebounded 40-35, falling to 1-3 when the opponent wins the battle of the glass.
Maik Kotsar made four straight foul shots to give SC a 71-67 lead and Kentucky could not respond. No other Wildcat had more than 10 points.
United Kingdom limited SC to just 37.7 (23 of 61) percent shooting from the floor. He came into the game averaging a modest 14.2 points per game but almost doubled it against the foul-happy Cats.
The teams combined for 31 fouls and 41 free throws in the marathon first half.
Only time will tell if both versions of Vanderbilt can become one NBA-caliber player. His plus-7 was the second highest figure on the team, trailing only Sacha Killeya-Jones at plus-8.
Quade Green, the starting point guard in 13 previous games, sat out a third straight game because of a back strain.
Calipari has a 708-197 all-time on-court record.
The second part will be much more optimistic, promise, but first we must sift through the wreckage of Gamecocks 76, Wildcats 68.
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