The Blues looked to get a foothold in the game after the interval, however Palace were still in relative control after their dominant display in the first-half.
As the game approached the hour-mark, Ola-Adebomi was again close to registering a hat-trick. Ozoh and Adaramola did well to win the ball back in the Birmingham final third, with the latter squaring it across to Ola-Adebomi.
The Palace No. 9 got the faintest of touches to guide it past Mayo, but it bounced back out off the bottom of the post and into the arms of the ‘keeper.
Birmingham saw more of the ball as the second-half went on and managed to pull a goal back. Femi Olofinjana looked as though he had come too far with the ball inside the box, as it was scrambled away, but second-half substitute Pharrell Williams got lucky to strike home unchallenged inside the box.
The hosts could’ve been up all night in search of more, but the Eagles put the game to bed as David Ozoh rifled in a fourth late on. After carrying the ball forward, the midfielder was slipped in by Umeh and held off a challenge to power home his second goal in three games.
Victory for Palace means that they move to the top of Group H at the halfway point in the group stage. Powell’s side currently have six points to their name, two clear of the Blues and Ipswich Town.
Birmingham: Mayo (GK), Olofinjana, Fogarty (Browne, 71), Fairnie, Home, Khela (Pendleton, 78), Dixon, Patterson, Kamara, Oakley, Ellis (Williams, 61).
Sub not used: Basey (GK).
Palace: Whitworth (GK), Imray, Grehan, Sheridan, Adaramola, Rodney, Ozoh (Reid, 90+3), Wells-Morrison, Mathurin (Raymond, 80), Ola-Adebomi, Umeh (Akinwale, 86).
Subs not used: Izquierdo (GK), Watson.