The summer signing believes there were promising signs in the Spurs display.
The Belgian lined up alongside countryman Jan Vertonghen at Old Trafford and the two showed signs of a growing understanding.
Spurs limited United to few chances - with their winner coming via an unfortunate Kyle Walker own goal – and fans will be encouraged after last season’s woeful defensive showing.
Alderweireld shared his optimism in an interview with the club's official site after the game:
"You’re never happy with a defeat but we have to be happy with how we played,"
"It’s always difficult at Old Trafford. We were right in the game, defensively we were strong and restricted them to very few chances which was good. If we keep at this level then the results will come."
The 26-year old was coy when asked about his own performance and instead chose to focus on the defence as a whole, adding:
"It’s difficult to talk about yourself after a defeat.”
"The stats say it all - we didn’t give them anything and defensively we worked very hard. We have to be confident for the Stoke game now and when we get our chances we have to take them."
He may have been less than forthcoming in his appraisal of his own game, but the new boy definitely impressed on his competitive debut.
His partnership with Jan Vertonghen has the makings of a special one, with both players extremely comfortable on the ball and mobile across the ground, and the return of Danny Rose and Hugo Lloris to the starting line-up should further strengthen the Spurs defence.
Kyle Walker also displayed a renewed focus on Saturday, and if those five can remain together consistently this season - the 'goals against' column should look a whole lot healthier come next May.