Ralph Hasenhüttl has praised the contribution of Jack Stephens, after the defender stepped back into the side following injury to Jannik Vestergaard and immediately helped the team to three consecutive clean sheets.
Vestergaard last featured in the home game against Manchester City ahead of Christmas, with a knee problem forcing him onto the sidelines and interrupting a season in which he had established himself as an early player of the season candidate.
If there was concern about the implications of that injury, they have since proved unfounded, as Stephens reignited his partnership with fellow centre-back Jan Bednarek and played an important role in blanking the attacks of Fulham, West Ham and Liverpool in the club's most recent three matches.
"This was not easy for Jack, coming out of the team after the first two games of the season where we have lost and then seeing the team playing that well without him," said Hasenhüttl.
"I'm very happy he showed the reaction now when he got back the chance to show up, and the way he did it in the last game especially against the ball was much more aggressive than I have seen from him before, and this is always the thing I was a little bit criticising with him, that he was sometimes not the most aggressive centre-back.
"But with the ball we know that he has big qualities, he was always one of the best footballers here in building up for our game, but now he has also the other part, like Jan Bednarek developed his part with the game massively. He was always the best defender I think, and now he is also with the ball getting better and better, so every player has to know if you want to be on a winning side then you must develop your game.
"Every weakness of your game you have to work on, and if you do this you have also the future chance to be part of the squad."
Saints' defensive improvement as a team has not only been evident in these past three matches. Over their last six Premier League games – against Sheffield United, Arsenal, Manchester City, Fulham, West Ham and Liverpool – Hasenhüttl's side have conceded only twice.
A big part of that development, the manager believes, is that they have become a better side at keeping the ball.
"This is the biggest change to be honest to the past, that we are better defending," he said. "We have been always a well organised team, but it is strange that we conceded so many goals, so that means we had to develop every part and every player – the goalkeeper and also everybody else against the ball must be even more disciplined, and since we play a little bit more football we maybe can also defend over 90 minutes more consistently.
"The game with the ball had an impact on our defence and in the moment we have a much better balance of keeping the opponent away from our goal. Against the ball we are always well organised I think and with the ball we are getting better and better."