Cardiff give Connacht the blues
The Blues scored three tries on the night through Olly Robinson, Matthew Morgan and debutant Owen Lane and led 30-18 with barely ten minutes remaining.
But Nick Williams' yellow led to a nervy final few moments as Connacht crossed twice late on through Shane Delahunt – the replacement hooker bagged a double in all – and John Muldoon to secure two losing bonus points in the Welsh capital.
Replacement Gareth Anscombe kicked two penalties in between those two scores that proved vital in giving the Blues victory that keeps them in touch with the top three.
Their Irish visitors had dominated proceedings in the early stages with only a Jack Carty penalty to show for it.
But after a Jarrod Evans penalty, Robinson went over after fine work from Lane and Willis Halaholo in the build-up.
Evans added the extras and a second penalty and his side led 10-3 before Niyi Adeolokun picked off an interception and raced clear under the posts.
Carty's conversion and subsequent penalty, plus another from Evans meant the Blues went in 16-13 to the good.
Eoin Griffin was shown a yellow card early in the second half and the Blues made that advantage count when Morgan ghosted over down the right.
And moments later Anscombe – who impressed off the bench released Tom James for what appeared to be the decisive score.
But it was ruled out for an unnecessary Nick Williams obstruction in the build-up and Connacht went up the other end and Delahunt went over at the back of a rolling maul.
However Anscombe then broke clear and fed debutant Lane who picked the pass of his toes and showed great awareness to roll over the line for a fine finish.
With that the game appeared over but another Nick Williams indiscretion saw the No.8 sent to the bin and in the end the Blues had to hold on tight.
But the victory means the Blues have done the double over their Irish opponents for the first time since the 2013/14 campaign.
For Cardiff Blues:
Tries: Robinson, Morgan, Lane
Cons: Evans, Anscombe 2
Pens: Evans 3, Anscombe 2
Tries: Adeolokun, Delahunt 2, Muldoon
Cons: Carty, Crosbie
Pens: Carty 2
Cardiff Blues: 15 Matthew Morgan, 14 Owen Lane, 13 Garyn Smith, 12 Willis Halaholo, 11 Tom James, 10 Jarrod Evans, 9 Tomos Williams, 8 Nick Williams, 7 Olly Robinson, 6 Macauley Cook, 5 Damian Welch, 4 George Earle, 3 Taufa'ao Filise, 2 Matthew Rees (captain), 1 Corey Domachowski.
Replacements: 16 Kirby Myhill, 17 Brad Thyer, 18 Anton Peikrishvili, 19 James Down, 20 Josh Turnbull, 21 Lewis Jones, 22 Gareth Anscombe, 23 Harri Millard.
Connacht: 15 Tiernan O'Halloran, 14 Niyi Adeolokun, 13 Eoin Griffin, 12 Tom Farrell, 11 Matt Healy, 10 Jack Carty, 9 Caolin Blade, 8 John Muldoon (captain), 7 Jake Heenan, 6 Eoin McKeon, 5 James Cannon, 4 Quinn Roux, 3 Finlay Bealham, 2 Dave Heffernan, 1 Denis Buckley.
Replacements: 16 Shane Delahunt, 17 Peter McCabe, 18 Conor Carey, 19 Gavin Thornbury, 20 Eoghan Masterson, 21 James Mitchell, 22 Steve Crosbie, 23 Pita Ahki.
Referee: Craig Evans (Wales)
Assistant referees: Simon Rees, Adam Jones (Wales)
TMO: Jon Mason (Wales)