The Reds were beaten 2-1 at Brighton & Hove Albion on Saturday in our first away match of the Premier League campaign, after Seagulls striker Joao Pedro headed a 95th-minute winner.
It was the sixth time since the 2022/23 season that United have lost a league game from a goal scored in second-half stoppage time.
Speaking in his post-match press conference at the Amex Stadium, Ten Hag insisted his team must keep going until the final whistle sounds.
“We have good potential but we have to keep going until the end because where we concede, in the Community Shield [against Manchester City], almost in stoppage time,” the manager told reporters.