Wright thumped O'Brien down the ground for the solitary six of the innings from the final ball of the 16th over but fell two balls later as Rankin returned and the Sussex all-rounder could only spoon off the toe end of the bat to extra cover.
Having lost all-rounder Andrew Flintoff to a side strain at the end of the first day, England suffered an early blow on day two as first-innings top-scorer Owais Shah was ruled out because of an eye problem.