Ralph Hasenhuttl believes Southampton have found the "belief" to step clear of the Premier League's relegation battle.
Michael Obafemi and Nathan Redmond struck to stun Chelsea as Saints pulled off a hugely-impressive 2-0 win at Stamford Bridge on Boxing Day.
Hasenhuttl's men have now bagged four victories in six league matches, in a sequence that followed an eight-game slump without a win.
Saints' Austrian boss hailed the Boxing Day win at Chelsea as the best result of the campaign, and challenged his side to keep their fine run going.
"That's by far the best performance this season," said Hasenhuttl.
"In the second half we showed that we can play, that we can put together some good passes.
"We stayed brave and tried to keep them far away from our goal.
"I can see a massive change in belief in what we're doing, organisation, behaviour after losing the ball.
"We are much better in counter-press, closing to the goal, give pressure to the front. We are braver in every part of our game.
"There's still a long way to go, but I think in the first two months we played like a relegation team; and now we play like a Premier League team."
Saints host Crystal Palace on Saturday in a quick-fire return to action that Hasenhuttl believes will be far easier to handle amid a winning feeling at St Mary's.
Redmond's goal at Chelsea capped a sweeping team move, leaving Hasenhuttl impressed with his side's confidence in possession.
"I think the second goal was the best example of how we can play and what we want to do," said Hasenhuttl.
"You could feel that today we were much calmer on the ball.
"We were really focused on winning. I'm so happy for Nathan (Redmond) because he was so hard working, I always tell him the goals will come.
"Michael (Obafemi) surprised everyone with his goal, but he was always there to help the team and that's the best Michael we can imagine."