Ferguson watched his team go 2-0 down to Tottenham Hotspur before slipping to a 3-2 defeat last weekend, handing Spurs their first win at Old Trafford for 23 years.
United have trailed in five out their six Premier League matches so far this season, a stat Ferguson is desperate to halt urgently.
He told reporters: "The first half against Southampton, the first half against Liverpool and the first half on Saturday, we have some work to do in that respect.
"It's not planned but I think it will be the last. You have to be concerned losing goals the way we did against Tottenham. We were well off the pace of the game. I don't think we won a tackle in the first half.
"Fortunately you saw Manchester United in the second half. It was probably our best performance of the season in the second half."
United get a chance to forget their Premier League form with a trip to Romania to face Cluj in the Champions League on Tuesday night.