Weaver went seven strong innings for OSU and gave up four runs on eight hits in a losing effort.
Jason Jaramillo went 3 for 4 and Mario Matulich drove in the only runs for the Pokes with his seventh dinger of the season.
The Cowboys dipped to 30-20 on the season and 12-11 in Big 12 play, while the Huskers improved to 38-13 and 17-6 in conference tilts.
Matulich staked the Cowboys to a two run lead in the top of the second with a two-run homerun to left.
Matt Hopper gave the Huskers the lead with a two-run single to left in the bottom of the fifth.
Alex Gordon added to the lead with a solo homer to centerfield in the bottom of the sixth.
Gordon led off the eighth inning with a double and scored on an RBI single by Bubbs Merrill to provide the final margin of 5-2.
The series will conclude at tomorrow at Hawks Field. Southpaw Spencer Grogan will take the hill for OSU and he will go up against righthander Phil Shirek of Nebraska.