Goals have been in short supply for winger Downing, but his second of the season secured another trip to Wembley in double-quick time.
The England international has not had the start he would have wanted to his Liverpool career and did not score his first until the third-round victory over Oldham in January.
However, if he is saving his best for the knock-out competition, manager Kenny Dalglish will be hoping there is more to come from the 27-year-old with a second trophy of the campaign now tantalisingly within their grasp.
And the Scot will be looking for more good omens as the club had not played in the last eight of the FA Cup since the last time they won the trophy in 2006.
But having ended a 16-year wait to play at the national stadium with last month's Carling Cup triumph, Liverpool are heading back to the capital once again - albeit for a semi-final.
As is to be expected against Stoke, it was a hard-fought encounter where - for once this season - the quality of Liverpool's finishing proved the difference.
Tony Pulis' side travelled to Anfield knowing the Potters had not won there for 53 years.
And although they did at least put an end to one bad run by scoring their first goal in seven FA Cup encounters against the Merseysiders courtesy of Peter Crouch, they never really threatened an upset after equalising Luis Suarez's opener.
The first half was all about Liverpool trying to establish some control and Stoke working their hardest to deny them, and for 20-odd minutes the pair almost cancelled each other out.
Maxi Rodriguez, on his first start since January 28, belied his diminutive stature to rise above the Potters' towering defence and nod over Steven Gerrard's early free-kick before Crouch, in a warning of what was to come, headed tamely at Jose Reina from Ryan Shotton's cross.
Martin Kelly and Glen Whelan were booked for late challenges on Matt Etherington and Jay Spearing, respectively, as the midfield battle warmed up.
Stoke's work-rate was causing problems to Liverpool's patient build-up play as the hosts were given no time to settle on the ball, but when the Reds ran at the Potters' defence it produced better results.
That was proved in the 23rd minute when Suarez picked up the ball in a deep position, advanced, bounced a pass off Rodriguez and whipped a low right-footed shot past Thomas Sorensen's left-hand just inside the post.
But within three minutes Stoke were level when Etherington's corner picked out former Reds striker Crouch to head home from five yards out, with Reina subsequently booked for claiming, correctly, it should not have been a corner in the first place and also that he was impeded by Shotton.
Andy Carroll volleyed over and Jon Walters failed to hit the target after running through the inside-right channel before he blasted the last chance of the half into the Kop from a free-kick on the edge of the penalty area.
Within a minute of the second half re-start, Gerrard had forced Sorensen into a low save while Suarez flashed a header across goal and wide of the far post from Downing's free-kick.
Downing played a more decisive part in the 57th minute when, after collecting the ball in the inside-right channel and fortuitously having it returned to him via Gerrard's backheel, he continued to the edge of the area before drilling a fierce left-footed shot past Sorensen.
The goal lifted Liverpool and Suarez's swerving low shot tested Sorensen down to his left again as the home side looked to force home their advantage.
Stoke began pushing harder for a second equaliser but they found Liverpool determined not to squander another lead.
In five minutes of added time the Potters forced a couple of corners and Rory Delap long-throws, but this time there was no lapse of concentration at the back.
Wembley is on the horizon again for Dalglish's side and with it the prospect of a second piece of silverware this season.