With time running out, the impressive O'Brien burst past Paul Warwick and threw a backhanded pass out of the tackle for the supporting O'Driscoll to run in from the right.
The home side started strongly and Steven McGarry had a 30-yard volley saved before O'Brien cut inside and played one-twos with Paul Quinn and David Clarkson before finding the net with a powerful low drive, which went in off Scott Severin.