The Villans goalkeeper has praised the role of the Dutch defender and club captain in Paul Lambert's team escape from the drop during his debut season in English football
Paul Lambert's side finished five points clear of the relegation zone after spending the closing weeks of the season in danger before Wigan were relegated at Arsenal.
And Guzan, who was also instrumental to Villa's bid to beat the drop, praised the contribution of Vlaar in his debut season in English football.
"Ron has been tremendous for us," Guzan told Aston Villa's official website. "It's always good to have a defender who organises - a guy who reiterates positions to help things before they happen on the pitch.
"He's an international defender who has played football at the highest level. His ability speaks for itself. He has commitment, strength and understanding of the game.
"What he's brought to the team has been massive."
Villa conceded 69 goals in the Premier League last season but despite leaking an average of almost two goals a game, Guzan believes Vlaar's no-nonsense defending was vital to the Villa cause.
"He's a true competitor - a real warrior, a real fighter. You need that in the Premier League," he continued.
"He's very vocal and a real organiser. That's important in any team. Ron brings that to the table.
"Just to have someone in the backline who is a real leader is a massive thing. Ron is a leader, no question."