The Reds continued their Barclays Premier League title challenge on Wednesday as they saw off their struggling visitors to move a point behind leaders Chelsea.
Gerrard's free-kick was followed up by Daniel Sturridge's 20th league goal of the season, before Ki Sung-yeung made for a tense finish.
Captain Gerrard is used to leaving free-kicks to leading scorer Luis Suarez and was just glad to be able to have a shot at goal.
"Credit to Sunderland, they came to shut up shop and made it difficult," he told Sky Sports 1.
"I don't usually get a go (at free-kicks). Luis Suarez has been magnificent on set-pieces but sometimes you need people to step in and I got it right.
"He let me take one! He wouldn't let me take one at Cardiff! But it doesn't matter who gets the goals. We've won nothing yet."
Sturridge has won plenty of plaudits, though.
He and Suarez have both got 20 league goals this season and he said: "It's a great feeling but it's more important for the team. It's not about personal accolades."
Reds manager Brendan Rodgers felt his side got their rewards for showing patience.
"It was always going to be really difficult. There's a perception that we're always going to score four or five every game," he said.
"There was a block of eight which was hard for us to penetrate.
"We had to be patient and then our quality came through. Our work rate was outstanding and we scored two excellent goals.
"We made the point that we had to show patience."
Asked if it was a win that marked them out as possible champions, Rodgers said: "Certainly it's a win that good teams grind out.
"We're one point behind and this is it. We will recover for the weekend."