Vesty's late drop-goal took Leicester clear of the Blues
Blues: (14) 17
Tries: N Robinson, Czekaj
Cons: Blair (2)
Leicester: (15) 21
Tries: O Smith, Varndell
Pens: Goode (2)
Leicester got their Heineken Cup back on course with a pulsating win against 14-man Blues at the Millennium Stadium.
Nicky Robinson and Chris Czekaj scored superb first-half tries for the Blues, but home mistakes allowed Tom Varndell and Ollie Smith to cancel them out.
Gary Powell's 52nd-minute sending-off for a head-butt proved decisive, as the Tigers forwards gained the upper hand.
Andy Goode's penalty and Sam Vesty's drop-goal sealed the win, although the Blues did secure a bonus point.
The Blues had targeted the Heineken Cup pool record attendance of 34,000, but will have been satisfied at attracting a club record 26,645 to the national stadium in Cardiff.
The large crowd saw an aggressive opening from each side before Robinson - controversially left out of the Wales squad last week - broke the deadlock.
The Blues backs showed the ability to cut Leicester apart
The ball came to him from a ruck in centre field and the Blues outside-half feinted right before heading left, chipping over the flat defence, and having the pace to score ahead of his own wing, Mosese Luveitasau.
Ben Blair converted, but the Tigers struck straight back when Czekaj lost the ball from an over-elaborate handling move at the base of a Blues scrum.
Harry Ellis hacked through, and from recycled ball Smith threw a dummy to cross in the shadow of the posts, with Goode converting.
Another complicated Blues switch move saw Tom Shanklin drop the ball and Shane Jennings kick through.
Possession came to Goode, whose pin-point cross-field kick reached Varndell to give the wing a clear run to the line.
Goode missed the conversion, but added a penalty conceded by the under-pressure Cardiff side's forwards at a scrum.
The fly-half became the villain when he missed touch straight afterwards, and Luveitasau sparked a swift counter attack.
Robinson flung the ball wide to Shanklin who straightened the line before sending Czekaj in at the corner, Blair converting.
Leicester took a one-point lead into the break, but were struck by the sight of seeing England centre Smith hobbling off with a serious-looking knee injury after a heavy tackle Shanklin.
The Tigers forwards increased the pressure at set-piece and breakdown after the break, and Goode landed a penalty after another scrum offence.
Ollie Smith suffered a serious-looking knee injury
Home frustrations boiled over from the next series of scrums, and tight-head prop Powell was red carded for a head-butt on George Chuter.
The 14-man Blues weathered a series of short-range scrums, and saw numbers temporarily evened as Varndell was sin-binned for stopping a quick Mike Phillips tap penalty.
Blair cut the gap to a single point with a fine penalty, and Goode missed a drop goal from underneath the posts.
But the officials failed to spot a penalty when Louis Deacon kicked the ball from Blues hands at a ruck five metres from the Tigers line, and at the other end a Vesty drop-goal rounded off the scoring.
Blues coach Dai Young:
"We could and should have won, although we take nothing away from Leicester - they were dogged and attacked us at the set pieces as we expected.
"At half-time I felt we had earned everything and gifted them their points.
"We planned to step up, but the sending off was disappointing and turned the game.
"We still could have sneaked the win, but we only have ourselves to blame.
"In big-match rugby little things matter, we have to learn from that.
"At least we got a bonus point, but we'll be under pressure in the double header with Munster. They are a machine, but we don't fear anybody."
Leicester flanker Lewis Moody:
"We played some great, frantic rugby for 20 minutes but then let it slip - it would have been nice to play more attractively.
"But it was all about the win and we got that against a form side at the Millennium Stadium.
"We got more control in the second half, but playing against 14 men can always be tricky, you never count your chickens.
"I think the pressure of having to win helped us. Now we have to get back-to-back victories against Bourgoin."
Blues: Blair; Luveitasau, Shanklin, Stcherbina, Czekaj; N Robinson, Phillips; Jenkins, Thomas, G Powell; Jones, Sidoli; Morgan, M. Williams, Lewis.
Replacements: Filise for Luveitasau (54), J Robinson for Stcherbina (56), Davies for Sidoli (76), Rush for Lewis (45).
Not Used: G Williams, Fairhurst, Macleod.
Sent Off: G Powell (52).
Leicester: Vesty; G Murphy, O Smith, Gibson, Varndell; Goode, Ellis; Castrogiovanni, Chuter, White; Hamilton, Kay; L Deacon, Moody, Corry.
Replacements: Rabeni for O Smith (39), Bemand for Ellis (68), Ayerza for Castrogiovanni (63).
Not Used: Buckland, B Deacon, Jennings, Burke.
Sin Bin: Varndell (58).
Referee: Alan Lewis (Ireland).