Both Raphael Varane and Lisandro Martinez were withdrawn in the first leg of their Europa League quarter-final with Sevilla, with the latter being taken off on a stretcher in the dying embers.
The severity of both players' unspecified concerns is unclear, but neither man should be fit to play a part on Sunday as Ten Hag works around an ever-growing injury crisis.
Marcus Rashford (groin), Donny van de Beek (knee), Luke Shaw (thigh), Tom Heaton and Alejandro Garnacho (both ankle) are also confined to the infirmary, while Scott McTominay is nursing a knock that will need checking over the next 48 hours.
As Varane and Martinez take their places on the sidelines, Victor Lindelof and Harry Maguire - who scored an incredibly unfortunate own goal on Thursday night - will pair up in front of David de Gea.
Tyrell Malacia's spot at left-back is safe despite also deflecting a cross into his own net, but a well-rested Diogo Dalot should challenge Aaron Wan-Bissaka for his right-back berth.
With Bruno Fernandes suspended for the second leg against Sevilla, the Portuguese should certainly keep his place alongside Casemiro, but two-goal hero Marcel Sabitzer could enjoy a break as Christian Eriksen comes in for his first Premier League start since January.
A distinct lack of senior options up front means that Anthony Martial, Antony and Jadon Sancho should all hold their places, unless Ten Hag gives consideration to a recall for Wout Weghorst amid any lingering concerns over the former's fitness.
Manchester United possible starting lineup: De Gea; Dalot, Lindelof, Maguire, Malacia; Fernandes, Casemiro, Eriksen; Antony, Martial, Sancho