Teenager Joseph Griffin slotted over a last-gasp penalty to rescue Cardiff Blues a deserved 23-23 draw against Exeter.
The Chiefs looked on course for an away win in the LV= Cup fixture played out at a rain-soaked Cardiff City Stadium when they led 23-12 at the break.
Tries from Simon Alcott and Nic Sestaret, plus three penalties and two conversions from Ryan Davis, gave the Aviva Premiership side a comfortable cushion after the first 40 minutes.
However Cardiff hit back in style; full-back Dan Fish grabbed a try, Gareth Davies kicked his fifth penalty and then Griffin levelled matters at the death.
A draw was no more than the Blues' second-half performance merited as they bravely opted to keep the ball in hand despite the tough conditions.
They had needed something special though after falling behind at the break.
Cardiff fly-half Davies kicked two penalties to Davis' one in the early going before Exeter claimed the opening try in the 17th minute, scrum-half Haydn Thomas setting hooker Alcott racing away down the touchline to score.
Davis added the conversion and then pushed the Chiefs further ahead with his second penalty, punishing Cardiff's inexperienced pack for another infringement.
Davies cut the gap to four points with his third penalty just shy of the half-hour mark - only for the Blues to concede a second try soon after.
Despite juggling the ball as he gathered it in, winger Sestaret managed to get on the end of a chip to the corner from Davis, who then proceeded to knock over the extras from tight to the touchline.
The two teams both traded penalties in between an injury to Alcott at a scrum, though thankfully he was able to walk off the field after treatment.
Having been second best for much of the opening half, Cardiff came out after the re-start and produced their best passage of attacking play leading up to Richard Mustoe putting Fish in at the corner.
Davies failed with his conversion attempt and then also scuffed a long-distance penalty.
The number 10, however, made no mistake with another shot at goal in the 76h minute; the three points setting up a rousing finish to the fixture.
Exeter looked set to weather the late storm - somewhat appropriate considering the weather - only for a high tackle to allow replacement Griffin, 18, to deny them at the death with a late, late penalty.
For Cardiff Blues:
Pens:G Davies 5, Griffin
Tries: Alcott, Sestaret
Cons: Davis 2
Pens: Davis 3
Cardiff Blues: 15 Dan Fish, 14 Richard Mustoe, 13 Gavin Evans, 12 Dafydd Hewitt (c), 11 Tom James, 10 Gareth Davies, 9 Lloyd Williams, 8 Tom Brown, 7 Josh Navidi, 6 Luke Hamilton, 5 James Down, 4 Bryn Griffiths, 3 John Yapp, 2 Gareth Williams, 1 Tom Davies.
Replacements: 16 Kristian Dacey, 17 Sam Hobbs, 18 Scott Andrews, 19 Macauley Cook, 20 Thomas Young, 21 Tom Slater, 22 Joseph Griffin, 23 Owen Williams.
Exeter: 15 Luke Arscott, 14 Nic Sestaret, 13 Phil Dollman, 12 Jason Shoemark, 11 Mark Foster, 10 Ryan Davis, 9 Hayden Thomas, 8 Richard Baxter, 7 Andy Miller, 6 Tom Johnson, 5 James Hanks, 4 Tom Hayes (c), 3 Hoani Tui, 2 Simon Alcott, 1 Brett Sturgess.
Replacements: 16 Chris Whitehead, 17 Ben Moon, 18 Ignacio Elosu, 19 Dave Gannon, 20 Dave Ewers, 21 Garrick Cowley, 22 Igancio Mieres, 23 Matt Jess.
Referee: David Jones