The Saints went ahead through James Ward-Prowse's opener after Nampalys Mendy gave away a preventable penalty after he brought Shane Long down in the box.
Young fullback Yan Valery received a second yellow card in the 45th minute to reduce the visitors to 10 men but Long doubled the lead just before the break. Wilfred N'Didi pulled one back for the hosts in the 58th minute, but that was as good as it got as the Foxes slumped to a second home defeat in as many games.
There was criticism from home supporters with one fan even donning a 'Puel Out' prior to kick off as the pressure seems to build on the Leicester manager.
'The fans are disappointed like us'
Puel acknowledged the fans' frustrations following the game as he spoke to Sky Sports. He said: during his post-match interview as he stated: "The fans are disappointed like us and it's a normal thing, it's not my concern, I have to keep my focus and concentrate on the team."
He added: "We wanted to perform, we wanted to have a reaction and our concentration was perhaps too much. It was a difficult scenario."
'We didn't manage the game well enough'
The Foxes boss spoke about the first half display and the poor passing that ultimately led to his team's demise.
Speaking further to LCFCTV, the Frenchman said: “We didn’t manage the game well enough in the first half and we conceded on the counter attack. We gave away an important ball to this team to put us under pressure on the counter attack for the penalty. We have to manage this better."
Southampton's second goal turned out to be the winner and the timing of it was unfortunate, according to Puel.
“We conceded the first goal but we had chances to come back. It was a good thing after the sending off to come back into the dressing room without conceding the second goal, but the second goal was harsh and it came at a bad moment.
"We played with desire and intensity in the second half but we didn't perform enough."