Substitute Gareth Davies scored a try three minutes from time, just five minutes after coming on, to give Cardiff a famous 19-15 win over champions Toulon in the European Cup on Saturday.
Toulon had led through most of the Pool 2 game as Jonny Wilkinson kicked five penalties.
But a Rhys Patchell penalty and three from Leigh Halfpenny had kept the Welsh hosts in the game until the dramatic finale.
Toulon No.8 Chris Masoe was at fault with a clumsy knock-on when under no pressure on his own 22.
Cardiff attacked from the resulting scrum with centre Owen Williams making a barnstorming run that took him through several tackles before he was brought down five yards out.
The Blues recycled the ball quickly and Davies danced through two tacklers and then managed to go over Frederic Michalak's shoulder before stretching out to touch the ball down over the line.
Halfpenny kicked the extras leaving Toulon needing to score at least a try in the remaining 90 seconds to avoid their first defeat in the competition since their final group game away to Montpellier last season.
Cardiff looked to control the ball from the restart but gave away a needless penalty with just five seconds remaining, allowing Toulon the chance to launch a desperate last attack.
But Cardiff's defence held firm and forced a turnover to secure a vital win.
Patchell had given them the lead on three minutes but two Wilkinson penalties put the champions ahead before the half hour mark.
A Halfpenny kick levelled matters before the break but two more Wilkinson scores from the tee opened up Toulon's lead to six points before the Cardiff full-back knocked over two more of his own to level up matters again.
Halfpenny then turned villain as his late tackle on winger Josua Tuisova gave Wilkinson the chance to land his fifth score nine minutes from time.
Yet Davies had the last word and Cardiff bounced back from their crushing defeat at Exeter last week to leave the group wide open.
In Pool 3 former Scottish international fly-half Dan Parks kicked 23 points as Connacht kept their qualification hopes alive with a thumping 33-6 win at Zebre.
No.8 George Naoupu and centre Mata Fifita scored tries while Parks kicked seven penalties and a conversion.
On Friday, a late Louis Picamoles try help Toulouse to a 17-16 victory at Saracens in front of more than 60,000 people at Wembley, leaving the four-time winners in charge of Pool 3.
Leicester winger Adam Thompstone's last minute try earnt the Tigers a bonus point in their 34-3 thrashing of Treviso in Pool 5.