Nigel Pearson - Leicester City must be ruthless after Southampton loss
Pearson's side frustrated the hosts for the majority of the game at St Mary's Stadium, but were undone by a Shane Long double late in proceedings.
Last seasons' Championship winners have now lost their last four games, and are without a goal since their 2-2 draw at Burnley in October, with Pearson lamenting a lack of attacking incisiveness.
"Our players worked hard but we were undone with some real quality," he said. "They were committed but didn't show enough quality to win the game.
"We've got to look to progress. We've got the quality but I don't think you can underestimate the leap that coming to the Premier League is.
"It's easy to just blame poor defending but you've got to be ruthless in both boxes and we haven't been recently.
"We've been unfortunate but the main issue is that we're not taking the opportunities when we get them."
Chris Wood went close as the game approached its climax, but Leicester were well beaten and have now slipped to 18th in the league standings.
But Pearson is confident that his side will improve, although he conceded that they were struggling to acclimatise to the ferocity of the Premier League.
"It's inevitable that there will be doubts from time to time but the players will help each other. I have no doubts about that," he continued.
"I know we're capable and we have continue to work hard. The shift in circumstances is big but it is what it is, you have to be able to deal with that.
"At the moment we're not dealing with it enough.
"For me, people seem to have a thirst for negativity. I don't except that, but becoming a Premier League side that is capable week in week out doesn't happen overnight.
"Getting here is tough, staying here is tough. But I believe we can do it."