Gacesa opened the second half with a layup for the Horned Frogs (5-2) and his 3-pointer capped their 7-0 run in the first 79 seconds, leading to a timeout from frustrated USC coach Kevin O'Neill. That was part of a 17-2 run that gave TCU a 47-33 lead after the Trojans (4-4) had gone ahead before halftime.
USC extended a strange pattern with its second consecutive loss. The Trojans opened the season by winning their first two games, lost the next two, then won two more games before their latest losses.
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Colorado State graduate transfer John Gillon has chosen Syracuse, giving the Orange a potential starter at point guard entering the 2016-17 season.
DeSean Murray, who averaged 20.2 points as a sophomore at Presbyterian, will transfer to Auburn to play for coach Bruce Pearl.
Former Kentucky guard Ed Davender, the only Wildcat with at least 1,500 points and 400 assists, has died. He was 49.