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Sancho has not featured for United since October's 1-1 draw against Chelsea due to "circumstances with fitness and mood".
Meanwhile, Martial's last appearance came in the victory over Manchester City at Old Trafford earlier this month when he was withdrawn at half-time.
The pair are back available for United ahead of the clash at Old Trafford, where the host leads 3-0 from last week's first leg.
"We have some issues," Ten Hag said. "I think tomorrow that Anthony Martial and Jadon Sancho will return in the game squad, but Scott McTominay will still be absent.
"I think also the next game [against Crystal Palace] he will be absent. We have to see how that process will go. And for the rest, I think everyone is fit."
United last won the Carabao Cup in 2016-2017 under Jose Mourinho, a season where the Europa League was also won and a campaign that represents the last time the club won a trophy.