"Steve Thompson justified his selection by scoring a goal, and I'm very pleased for him," Jones said.
"He worked very hard throughout the match, and I was delighted with his performance.
"Southampton are young and athletic and were in our faces from the start, and although we were a bit sloppy in the opening half-hour, we battled away well and fully deserved the victory.
"It was very important for us to start with a victory, and by putting on two strikers, something I haven't been able to do in the past, we kept up the momentum, and now we can look forward to the next match with confidence."
Meanwhile Southampton boss Jan Poortvliet felt his side deserved a share of the points.He added: "Both sides would have been happy with a point, but we should have cleared the ball long before they scored their winner.
"I was satisfied with the first half, particularly the opening 30 minutes, but then Cardiff came into it and they worked very hard."