An early header from diminutive Emanuele Giaccherini at St Mary's looked set to secure the Black Cats' first win of the season.
However, Jose Fonte's last-gasp header secured Saints a deserved 1-1 draw and strengthened Di Canio's resolve when it comes to improving his squad further.
"When I asked 45 days ago for another central midfield player with a physical presence, with good quality and ability, preferably British, there was a reason," the Italian said.
"I know this league better than some managers who have managed for 20 years in England. I know, this is why I continually asked for two more players with a physical presence.
"I had the same situation two years ago at Swindon, a different level. We brought 12, 13 players from abroad and straight away I said I wanted two, three British ones with a physical presence.
"At the end of the season we won the league. Obviously I can't promise we'll win the league here but it is obvious that we will have less problems."
Di Canio did not enjoy the best preparation for the match, having been involved in a late-night altercation with drunk Southampton fans.
His side looked unaffected, though, and he was proud of the way in which they dealt with Saints' attack.
"I feel 50-50," Di Canio said. "Obviously we defended for the whole game, like Fulham did against us last week.
"The defence have done an amazing job because playing Lambert, Rodriguez, Lallana and then Ramirez and Osvaldo - I tell you, this is one of the best sides up front in the league.
"Their frontline gives them a chance for them to finish in the top 10, play good football, a physical presence, energy and quality.
"My back four, central midfield and wingers, have done a very, very good job in defensive moments."