A stunning 15 ball 40 by Rob White set the Northants Steelbacks on the way to a 17 run victory over the Warwickshire Bears at Wantage Road.
After winning the toss the Steelbacks got off to a flying start thanks to White and opening partner Ian Harvey.
The pair put on a partnership of 47 before White was caught by Chris Woakes off the bowling of Keith Barker.
Despite losing White the Steelbacks kept the pressure up on the Bears as O'Brien (42) and Nicky Boje (45) scored with ease after Harvey was dismissed for just 12.
Johan van der Wath came in at the end to hit a quick fire 22 to set the Bears a total of 177 to win.
In reply the Bears never stayed up with the run rate despite a fine display from Jim Troughton who scored 53 before being trapped lbw by Harvey.
Once Troughton departed Harvey came to the fore finishing with figure of 4 for 18 to lead the Steelbacks to a 17 run victory.