West Ham 0 Portsmouth 1: Niko Kranjcar's 61st-minute strike kept Portsmouth on the winning path after their weekend Wembley heroics and left the manager's former club West Ham in deep gloom.
Kranjcar drilled in a pass by Arnold Mvuemba for his fifth goal of the season, and made all West Ham's first-half superiority count for nothing even though David James had to produce a fine save to deny Dean Ashton.
Despite ample possession West Ham failed to fire again after early near-misses and Kranjcar was just over with a superb shot from David Nugent's pass a few minutes before scoring.
As West Ham made a late effort to save at least a point, James had to come charging off his line and did just enough to put off Sears, reacting to Carlton Cole's blocked shot. The young striker ran the ball out for a goal kick with the goal gaping.