Southgate's team selection was met with a mixed response, particularly after his side's 12-match unbeaten run came to an end, but Maguire - one of those to drop out of the XI - is hopeful that the big call will pay off against Colombia in the last 16.
"He's a brave manager and he makes big decisions in big times," he is quoted as saying by Sky Sports News. "You can say he is brave but so is [Belgium manager] Roberto Martinez - he also made a number of changes (9). I think they were both probably looking at the bigger picture and know that the next game is the biggest one of them all.
"Gareth is a man of great knowledge. He fills you with confidence no matter what decision is made. We all trust him as a group and hopefully it's the right decision in the long run. It's only a good decision if we go and put in a performance in the next game and qualify for the quarter-finals."
England will face either Switzerland or Sweden in the quarter-finals should they overcome Colombia in the first knockout round.