The 25-year-old is currently on loan at St Mary's from Atletico Madrid and is now an integral part of the most miserly defence in English football.
It was in attack where Southampton made the headlines on Saturday as they dished out a mauling to a Sunderland side who were simply blown away by the forward players on show for the hosts.
The Black Cats did little to help their own cause as Santiago Vergini hammered in an own goal that will live long in the memory to put Southampton on their way to their biggest ever Premier League win.
Player of the month Graziano Pelle continued his impressive start to the campaign by tapping in a second before Jack Cork added a third before half-time.
A second own goal from substitute Liam Bridcutt made it four, then Pelle completed a brace before Dusan Tadic, Victor Wanyama and Sadio Mane also got on the scoresheet.
Sunderland were unfortunate not to be awarded a penalty at 2-0 when Fraser Forster came off his line and appeared to bring down Steven Fletcher - although referee Andre Marriner was unmoved.
The rout means Southampton hold on to third spot in the Barclays Premier League table with manager of the month Ronald Koeman continuing his impressive start to life in English football.
Stoke are the next visitors to St Mary's next weekend but Alderweireld, who lifted the Primera Division title with Atletico last season, knows the players need to remain grounded as they look to build on such a memorable result.
"Of course we can be very satisfied with the result," he said.
"The second half was much better than the first but we have to keep calm
It is only three points and next week will be tough.
"We can be happy but from tomorrow we have to be focused on Saturday because it is a big day again
It can change very quickly in the Premier League."
The start to the season has seen Koeman and his players defy the odds after it was suggested they would struggle having lost the likes of Rickie Lambert, Adam Lallana, Dejan Lovren, Luke Shaw and Calum Chambers over the summer.
But in players like Alderweireld, as well as Pelle and Tadic who both impressed once again on Saturday, Koeman has remodelled his squad into a side who look capable of continuing such form.
Mauricio Pochettino led Saints to a best-ever eighth place Premier League finish last year before departing for Tottenham but Alderweireld feels that can be beaten this year.
"I think better than last season," the Belgium international answered when asked what Southampton should aim for this campaign.
"If we can make that step and finish in a better position that last season we can be happy.
"I knew a lot of players that Koeman brought and knew we had a good team
I signed here for a year to play good football and play with good players.
Wes Brown was replaced at half-time by Bridcutt but had already seen enough to know that Sunderland were nowhere near good enough.
Although the 35-year-old felt that Fletcher should have been awarded at 2-0, the former Manchester United man confessed it would not have papered over the cracks.
"We didn't manage to get the penalty and we are disappointed with that decision," he said.
"Had that been given it might have changed the game, he could have been sent off too, especially if we had put the ball in the net from it.
"It would have been 2-1 at the time
But it was not good enough today
There were not enough of us alive
To concede eight says it all really.
"There were too many of us off our game
we might have had 10 minutes, but then they got a goal, got a second goal and a third
We needed to come out and show some fight and we didn't do that.
"It has to be a one-off, you can't do that in the Premier League
You get punished like that if you do
We have to put this behind us as quickly as possible."
Source : PA
Source: PA