The Western Force have unleashed a six-try blitz to stun the Queensland Reds 40-31 in their Super Rugby Pacific showdown at Perth's HBF Park.

The Force raced out to a 21-0 lead inside 32 minutes on Saturday and were ahead 40-19 with 16 minutes to go, before the Reds launched a late fightback.

Tries to Fraser McReight and Jock Campbell closed the margin to nine points with five minutes remaining, but the Force held firm to deny the Reds a win or a bonus point.

The Force's first victory of the season resulted in the unthinkable - relegating the mighty Crusaders (0-5) to the bottom of the ladder.

Queensland (3-2) slipped from second to fifth.

"It was unreal," Force captain Jeremy Williams said of the win.

"We were very disciplined, and we were very patient when we were holding the ball.

"We executed really well. Our defence for the most part was really good.

"It's pretty special. To see all the stuff we've been doing at training replicated on the paddock was really good."

The Force entered Saturday's match with a 0-4 record and with coach Simon Cron declaring the time for talk was over.

Cron's men defended grimly early on against the Reds, and their hard work paid off.

A quickfire counter-punch resulted in winger Bayley Kuenzle crossing in the 15th minute.

The Force's hardness at the contest helped create their second try, with a counter-ruck on the Reds' line allowing Thomas Franklin to touch down.

And it was 21-0 when an unmarked Chase Tiatia went over on the wing.

Reds halfback Tate McDermott briefly stemmed the bleeding with a 35th-minute try - but his counterpart Nic White answered just 10 seconds before halftime to give the Force a 28-5 lead at the break.

McDermott scored his second try 90 seconds into the second period, selling a dummy to White and strolling over.

But Harry Wilson's fumble of the restart handed the Force an instant reply, with the ball bobbling off the back-rower's arms and head before Kuenzle ran in to snatch it and race to the line.

"Those things can happen," Reds coach Les Kiss said of the fumble from Wilson.

"People don't make mistakes like that on purpose, but those things were costly."

There was a big thump of frustration from the Reds' coaches box when Force flanker Carlo Tizzano fended off Ryan Smith in a 25-metre run to the line in the 54th minute.

Queensland sparked hope of a fightback with the final two tries of the match - but it was too little, too late.

The only downers for the Force were the loss of skipper Williams to a calf injury in the 27th minute, and a concussion to flanker Will Harris.

Reds centre Josh Flook was forced off in the second half following a head knock.