Exeter Chiefs thundered into a 41-3 lead before being pegged back by Cardiff Blues to win 44-29 at Sandy Park in the Heineken Cup.
The visiting Blues scored 26 unanswered points in the second half as they almost made up for a shocking first period with four tries, taking a bonus point back to Wales.
Cardiff's resurgence in the second half didn't make their abject performance from the first 40 forgettable, but was a seismic improvement.
It came too late overall though. Exeter had comfortably amassed 40 points and six tries in an accomplished performance, before their second-half collapse due to substitutions and two yellow cards.
The Blues at their worst were absolutely shambolic. It was a horrifying contrast to the success of the Scarlets at The Stoop the day before, when Welsh regional rugby had appeared to be on the rise again. This was a splash in the face.
19 tackles were missed by the visitors in the first half, as their paper-thin defence was repeatedly scissored apart by Exeter's persistent desire to run rather than put boot to ball.
Through little more than successive phases the Blues were cut open by Exeter's big carriers; Dave Ewers, Phil Dollman and the outstanding Tom Johnson all finding space.
Johnson was everywhere in the opening half-hour before being taken off due to an injury, putting his hand up for England recognition ahead of next month's November Internationals.
A sustained passage of running rugby from the home side yielded the game's first try, Exeter using their back-row effectively as Ewers and Johnson carried on multiple occasions during an 80-metre surge towards the Cardiff line. In the end it was Johnson who crossed over in the right-hand corner.
Halfpenny added the Blues opening points after Ian Whitten was penalised for holding on but Exeter domainted early possession and territory, Steenson adding three of his own for an 8-3 lead after 20 minutes.
The Chiefs afternoon got even better when captain Dean Mumm galloped through, the former Wallaby scoring his fourth try in only six matches so far this season as the Blues payed the price for a stolen lineout within their own half.
By the time Matt Jess scampered through almost from the restart, the Blues were already pondering their journey home.
Exeter were hungrier for the ball at the breakdown and played at a ferocious pace to wrap up a try bonus point after half an hour, Fetu'u Vainikolo gliding inside Alex Cuthbert for the fourth try and a 29-3 scoreline.
By the time Ben White flopped over for the Chiefs' fifth try of the first-half, and a 33-point lead, Blues fans were left already mapping their route back to Wales.
The Blues performance couldn't get any worse and there were signs of life from Alex Cuthbert after the break, the Lions winger putting the visitors in a dangerous position only for the opportunity to go begging.
Exeter continued to control the pace of the ball at the breakdown as Sam Warburton and his men were continually nullified at the contact area.
Whitten sprinted over after being released by Steenson's pass for the sixth try and the 40-point mark, a minute before Lloyd Williams snapped up a loose ball at the side of a ruck and ran in behind the defence.
It was a consolation try the Blues barely deserved, but it did give the Blues a spark. Exeter had controlled the breakdown for so long, but another loose ball out the side handed Robin Copeland a free run to the line as the Blues chased the possibility of a try bonus-point.
The Chiefs were then reduced to 13 men within a minute, as Whitten committed a deliberate knock-on and replacement Sireli Naqelevuki a high tackle. Momentum, dramatcially, had swung in the Welsh side's favour.
Cuthbert's calm finish for the Blues' third try turned that 41-3 scoreline into 41-22, Exeter's numerical disadvantage proving crucial as an injury momentarily reduced them to 12 to leave Harry Robinson with plenty of open space to grab that bonus-point score.
A penalty from young replacement Henry Slade calmed any jittering nerves for the Exeter fans, who bizarrely had been left sweating have lead by 38 points earlier in the second half.
Blues replacement Marc Breeze was shown a yellow card in the dying minutes for a tackle, but the Chiefs were already home. A bizarre game had Exeter taking five Pool points, but it wasn't as simple as everyone expected at half-time.
Tries: Johnson, Mumm, Jess, Vainikolo, White, Whitten
Cons: Steenson 4
Pens: Steenson, Slade
Yellow Cards: Whitten, Naqelevuki
For Cardiff Blues:
Tries: Williams, Copeland, Cuthbert, Robinson
Cons: Halfpenny 3
Yellow Card: Breeze
Exeter Chiefs: 15 Phil Dollman, 14 Matt Jess, 13 Ian Whitten, 12 Jason Shoemark, 11 Fetu'u Vainikolo, 10 Gareth Steenson, 9 Dave Lewis, 8 Dave Ewers, 7 Ben White, 6 Tom Johnson, 5 Damian Welch, 4 Dean Mumm (capt), 3 Hoani Tui, 2 Chris Whitehead, 1 Brett Sturgess.
Replacements: 16 Jack Yeandle, 17 Ben Moon, 18 Carl Rimmer, 19 Don Armand, 20 Kai Horstmann, 21 Haydn Thomas, 22 Henry Slade, 23 Sireli Naqelevuki.
Cardiff Blues: 15 Leigh Halfpenny, 14 Alex Cuthbert, 13 Cory Allen, 12 Dafydd Hewitt, 11 Harry Robinson, 10 Rhys Patchell, 9 Lloyd Williams, 8 Andries Pretorius, 7 Sam Warburton, 6 Josh Navidi, 5 Filo Paulo, 4 Bradley Davies, 3 Tau Filise, 2 Matthew Rees (capt), 1 Gethin Jenkins.
Replacements: 16 Marc Breeze, 17 Sam Hobbs, 18 Scott Andrews, 19 Lou Reed, 20 Robin Copeland, 21 Lewis Jones, 22 Gareth Davies, 23 Richard Smith.
Referee: JÃ©rÃ´me GarcÃ¨s (France)
Assistant referees: Patrick Pechambert (France) SÃ©bastien CloutÃ© (France)
Television match official: Philippe Bonhoure (France)
Timekeeper: Eric Bullion (England)