Downing registered his first league assist for the Merseysiders in setting up Steven Gerrard - after Martin Skrtel's opener - and capped his performance with a goal of his own before Luis Suarez added an injury-time fourth.
Despite a stellar performance, the England international played down his role as Liverpool bounced back in emphatic style from last week's 3-1 home defeat against Aston Villa.
"Coming off a bad result against Villa, we let ourselves down, and the manager said we had to bounce back tonight and I thought we did that in style," he told ESPN.
"I'm just trying to work hard and take the opportunity when I'm given it.
"I'm here to play and as long as I get the opportunity I'll try my best."
Both Downing and defender Skrtel are now desperate to use the win as a springboard to greater things after Liverpool moved up to eighth in the Barclays Premier League.
"I think we've been a bit nervy at home at times but I think it's time to get a ruthlessness at home," said Downing.
"The goals you've seen tonight are four quality goals and it's a case of doing it consistently and not now and again.
"We need to kick on in the new year and climb the table."
Slovakia international Skrtel added: "We've got a target for the top four at the end of the season and now we just want to be as close as we can."
Only last week Downing had admitted he may leave in the January transfer window after manager Brendan Rodgers said he could go.
The £20million signing has been held up as an example of Liverpool's wastefulness in the transfer market over the last few years.
Previous manager Kenny Dalglish certainly did not get his money's worth out of the winger and Rodgers has so far hardly attempted to as this was only Downing's sixth Premier League start of his reign.
He has mostly been confined to the Europa League and has even been played at left-back occasionally as Rodgers tried to find some use for him.
Rodgers was quick to hail the 28-year-old tonight, however, and insisted he never wanted Downing to leave Anfield.
"Stewart's been brilliant, he's a real good guy. I want him to be a part of the group here but at his age, we talked at him playing regularly and if the opportunity had come for him to go then him and I would look at it," said the Northern Irishman.
"But the reaction from that conversation six or seven weeks ago has been outstanding.
"He's played a lot of games and today I thought he was brilliant.
"If he keeps playing like that then he'll be in the team so there's no need for him to leave to get a game.
"I always have wanted him to stay. it's not about me pushing him out the door, he's a quality player.
"When you arrive in the latter part of your twenties and you want to be playing regular and obviously he wasn't at the time."
Of his side's overall performance, Rodgers added: "We performed as well as that in a lot of the games to be honest but never always got the result.
"Today [Saturday] was outstanding in every element of our game."
Martin Jol admitted Fulham had let themselves down.
"We conceded cheap goals and then we played against ourselves because there were too many disappointments," said the Dutchman.
"Overall it wasn't good enough."