Idrissa Gueye, a young striker from Metz, is considered as a potential backup for Serhou Guirassy at Borussia Dortmund. With a market value of 4 million euros, Gueye is an affordable option. However, his development could be hindered as he might spend most of his time on the bench. Additionally, Dortmund would need to sell Sébastien Haller, who has a high salary of around 10 million euros, before acquiring Gueye.