The Cornhuskers (11-10, 2-6 Big Ten) won for the first time in four conference home games.
Brandon Ubel had 14 points and 12 rebounds, and Gallegos added 11 points.
Ubel made two free throws and converted Gallegos' pass through the lane into a dunk at the front end of a 16-7 spurt that gave Nebraska a double-digit lead in the middle of the second half. Gallegos followed Shavon Shields' three-point play with three straight 3s to make it 44-33.
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SMU has signed a second player from Australia, 6-foot-11 forward Harry Froling, to a national letter of intent. The Mustangs previously signed guard Tom Wilson from Australia.
There's nothing to suggest the Jayhawks won't end up atop the Big 12 for a 13th season in a row. But what about a return to the Final Four?
Colorado State graduate transfer John Gillon has chosen Syracuse, giving the Orange a potential starter at point guard entering the 2016-17 season.