The Hammers have reportedly made a £17.5m bid for the 28-year-old forward as they look to strengthen their attack ahead of next season.
The player only joined Dortmund last summer; but, after making 30 appearances, he's now set for a move to the Premier League and should put pen to paper in the coming days as long as he passes a medical.
Zaha, meanwhile, has attracted plenty of suitors this summer. The winger is undoubtedly the Eagles' most potent source of offence and they are unwilling to let him go. Yet English papers are reporting that he has only recently turned down a new £125,000-a-week contract offer from the London side.
Manchester City, Tottenham Hotspur and Chelsea have all been linked with the electric speedster, but it appears Dortmund have now joined the race for the player, who was instrumental in keeping Palace up after returning from a lengthy absence last season.
The German side are in transition, having brought in a new manager in Lucien Favre. They also sold Pierre-Emerick Aubameyang to Arsenal back in January but are hoping to keep Michy Batshuayi, with the Belgian having spent the second half of the season on loan from Chelsea.
One would imagine a pairing of Zaha and Batshuayi up front next season would yield plenty of goals. However, that is still a long way from happening.