Mads Hermansen saved a shot from Samuel Iling-Junior before West Ham opened the scoring through skipper Bowen. Josh Sheehan could only divert Kyle Walker-Peters’ pull-back towards Bazunu, one of seven changes from Saturday’s 4-0 implosion at Millwall, and, under pressure from Pablo, he knocked the ball to Bowen, who rifled it home.
Back came Bolton and when Mavropanos could only half clear the ball towards the edge of his penalty box, Erhahon was on hand to shoot home his first Wanderers goal off the Greek defender.
Iling-Junior wastefully shot wide before Rodrigues fired Wanderers ahead from the penalty spot in the 27th minute with his first goal of the season when Walker-Peters caught debutant Kyliane Dong.
The contest then became more like a basketball game and the Hammers levelled four minutes later when Arne Engels sent over a teasing free-kick to the back post, where Mavropanos headed home.
The Hammers centre-back was denied a second by Bazunu when the Irishman made a fine reaction save to keep out his header.
West Ham pushed for a winner and Manor Solomon, Joel Piroe and Mohamadou Kante went close before Bowen settled the contest.
Substitute Joel Veltman crossed from the right and Bowen’s shot lacked power, but had enough to beat Bazunu to condemn Wanderers to their fourth straight Championship defeat.
However boss Steven Schumacher can take much heart from his side’s vastly-improved display from their defeat at the New Den.