Less than a year after winning the title, Leicester are fighting the drop and a 2-0 reverse at the Liberty Stadium represented a fifth successive top-flight loss without scoring.
That run has seen manager Ranieri come under increasing pressure, with the champions just a point clear of the bottom three.
But a frustrated Drinkwater has backed the former Chelsea boss, who received a vote of confidence from the club this week.
"Of course we are [behind the manager]," he told Sky Sports. "It is down to us on the pitch. The manager has our support and we have his support.
"The chairman [Vichai Srivaddhanaprabha] is backing everyone, too, so it's about time we showed that belief on the pitch."
1 - No team in the top four tiers has won fewer points in 2017 than Leicester (1, level with Aston Villa, Coventry & Leyton Orient). Bleak.— OptaJoe (@OptaJoe) February 12, 2017
Drinkwater could not offer any explanation for why Leicester's form has been so poor this season, though.
"It is frustrating," he said. "It is hard to put it into words. We need to get out of this.
"If we keep on fighting, hopefully, it will turn. We need to keep on pushing ourselves, force it and make sure we turn it around.
"We need to keep fighting for every ball. We are a bunch of honest lads. We work hard and we know everyone is disappointed - we are more than anyone.
"But it's another loss. It's not acceptable and we need to get things right pretty quickly.
"We have not changed much. It seems to be that maybe we are not getting the rub of green or something. We believe in ourselves. As long as we keep our heads, I am sure it will come."