Juan Ugarte struck twice in the first half to send Wrexham through to the semi-finals of the FAW Premier Cup at the expense of Haverfordwest.
The Spanish striker pounced on a loose ball after just seven minutes to open the scoring for the title holders.
Ugarte struck again at Bridge Meadow on the stroke of half-time, following up to poke home after Mark Jones' shot.
Colin Loss gave Haverfordwest hope just after the break when his cross sailed into the net, but Wrexham held on.
Haverfordwest, cheered on by a good and enthusiastic crowd, can at least console themselves with the £15,000 prize thay earned for reaching the quarter-finals.
Any Wrexham nerves, and Haverfordwest ambitions, were calmed as early as the seventh minute as the visitors grabbed the lead.
A ricochet fell kindly to the feet of Ugarte on the edge of the Haverfordwest area, who had all the time he needed to score as the home defence failed to close him down.
" When they scored the early goal in the second half we were under pressure, but the lads came through "
The striker from the Basque region struck a sweet left-foot shot low past stranded home goalkeeper Lee Kendall.
Haverfordwest, with a strong wind blowing in their faces, struggled to create chances and had just a couple of Lee Brown shots that sailed high over Xavi Valero's crossbar.
At the other end Haverfordwest were living on their nerves.
First Wrexham were denied what looked a certain penalty when Matt Brown was chopped down in the box as he bore down on goal.
Then Kendall produced an excellent save to keep out Hector Sam's shot from Carlos Edwards' cross.
Just a minute before half-time Wrexham doubled their lead when Mark Jones' sublime chip was just tipped onto the bar, only for Ugarte follow up to claim his second of the night.
But the Bluebirds from Pembrokeshire clawed their way back into the match immediately after the restart thanks to a mistake from Valero.
" We threw everything at them, but fair play to Wrexham they held out "
The Spanish keeper failed to judge Loss' free-kick from wide out and the wind-assisted punt sailed over his outstretched hand and into the Wrexham net.
With their tails now up, Haverfordwest started to match their full-time opponents in the middle of the park.
But the Welsh Premier side were limited to speculative long-range efforts as they tried to catch Valero off-guard again.
As the match entered its final quarter, Wrexham's greater fitness levels began to tell and Ugarte nearly grabbed his hat-trick with a curling right-foot shot.
Wrexham substitute Jamie Reed went inches wide from putting the result beyond doubt with three minutes remaining.
But Haverfordwest were unable to carve out an equaliser to take the match into extra time, and it is defending champions Wrexham who advance to the semi-finals.
Haverfordwest County (from): Lee Kendall, Ian Kerrison, Dave Barnhouse, Dylan Blain, Deryn Brace, Rob Jones, Wyn Thomas, Ritchie Adams, Phil Catlin, Lee Hudgell, Colin Loss, Lee Palmer, Dean Rossiter,. Niko Algieri, Lee Brown, Tim Hicks.
Wrexham (from): Xavi Valero, Michael Jones, Craig Morgan, Dennis Lawrence, Steve Roberts, Simon Spender, Andy Holt, Carlos Edwards, Matt Crowell, Levi Mackin, Matt Done, Mark Jones, Dean Bennett, Juan Ugarte, Hector Sam, Jamie Reed.