Asked if he had put himself under pressure Southgate said: "Maybe I have, maybe I haven't".
It means England go to Moscow to face Group H winners Colombia at the Spartak Stadium on Tuesday with Belgium meeting Japan in Rostov-on-Don on Monday.
By winning the match and thus the group, Belgium moves to the "side of death" for the knockout round, where four of the top five teams in the world according to Federation Internationale de Football Association rankings - Brazil, Belgium, Portugal, and Argentina - will all compete for one spot in the final.
Southgate also said he was ready to accept any criticism that would come with the defeat, but said he had achieved his "primary objective" by resting his players.
"We weren't focused on that [paths to the final] before the game, we want to win every game possible and we're disappointed, that's the main thing", the 19-year-old said.
In a weird game, England made eight changes and Belgium nine as two B-teams contested first place in Group G, knowing that topping the group placed the victor in a far tougher half of the draw.
"I'm entirely comfortable with the decision".
"I don't think you can plan the ideal scenario", the Spaniard said, noting the travails of Germany and other top teams so far.
"He was excellent on that, showed real leadership and understanding of the big picture".
"The players who've played tonight have given absolutely everything and never stopped". The depth of knowledge and understanding, we didn't have as much information as we do now.
Qualifying for the knockout stages in second place has sent the Three Lions into a preferable half of the draw for Canaries fans - if they can get past Colombia in the last 16. "Some outstanding individual players but we feel we are a team that is improving".
Wiltshire Police is urging suburban pubs to make sure they are prepared properly for World Cup games, after responding to reports of "trouble" at a crowded local pub.
"I think if I'd kept it on the floor and get a bit of extra detail on the finish it maybe has the chance of going in the far post".