After all other fighters made weight, Diaz tipped the scale at 169 pounds, and St-Pierre clocked in at 170 pounds.
However, for their customary faceoff, the main eventers both got in a fighter's stance, quickly got their arms tangled (largely due to Diaz), and were instantly separated by UFC President Dana White before the bad blood spilled over a day early.
The fighters traded barbs at Thursday's press conference after weeks of trash talk in the media. With today's brief scuffle quickly extinguished, though, the attention now turns to Saturday's big event.
MAIN CARD (Pay-per-view, 10 p.m. ET)
Champ Georges St-Pierre (170) vs. Nick Diaz (169) - for welterweight title
Carlos Condit (169) vs. Johny Hendricks (171)
Jake Ellenberger (170) vs. Nate Marquardt (171)
Chris Camozzi (185) vs. Nick Ring (183)
Colin Fletcher (155) vs. Mike Ricci (156)
PRELIMINARY CARD (FX, 8 p.m. ET)
Patrick Cote (169) vs. Bobby Voelker (169)
Antonio Carvalho (145) vs. Darren Elkins (145)
Jordan Mein (170) vs. Dan Miller (171)
Daron Cruickshank (155) vs. John Makdessi (155)
PRELIMINARY CARD (Facebook, 6:35 p.m. ET)
Quinn Mulhern (168) vs. Rick Story (169)
TJ Dillashaw (135) vs. Issei Tamura (135)
Reuben Duran (135) vs. George Roop (135)Link Weigh In Video