Saints were stung by a late Leicester comeback as a thrilling encounter ended in a 19-19 draw at Welford Road.
Jim Mallinder’s men had looked set to claim their first win at Tigers since 2007 as a first try for the club from Alex Corbisiero and 14 points from the boot of Stephen Myler gave them a 19-9 lead.
But Tigers came roaring back and a 76th-minute score from Ed Slater allied with a conversion from Flood, who, like Myler, racked up 14 points, ensured it was to end in deadlock.
Both teams finished the game with 14 men as Courtney Lawes and Louis Deacon were sin-binned with 10 minutes to go.
And it was to be Tigers who finished the strongest in the absence of their man to ensure Saints were unable to claim the bragging rights.
But the force from Franklin’s Gardens issued a statement of intent for the current Premiership campaign as they again showed they are capable of picking up points on the home turf of their title rivals.
Saints had demonstrated their desire to take the game to Tigers from the off and dominated possession in a big first half-showing.
The home team had suffered a blow before kick-off as Lions lock Geoff Parling was unable to take his place on the bench.
And when the game started, they soon had another injury issue to worry about as Sam Dickinson’s tackle saw full-back Blane Scully needing treatment inside 21 seconds.
Tigers, revved up by that incident, smashed Saints at the scrum and pushed forward to win a penalty that Flood put short of the posts from near halfway.
The home side again showed their teeth at the second scrum, powering to another penalty, but a huge hit from Luther Burrell won back possession for Saints.
That gave the away side the go-forward they were searching for and they earned a penalty on halfway that Myler made to put his men 3-0 up.
Saints were playing with plenty of belief and Myler kept the pressure on by booting a kickable penalty to the corner.
Tigers held out, though, and they were soon level as Burrell was binned for a dangerous tackle on Anthony Allen and Flood made the resulting penalty.
Saints, who had suffered three cards in the previous three meetings with Tigers, had a big 10 minutes coming up. They were to deal with it well.
Myler put them back in front as Dickinson won a shot at goal before another Tigers infringement near halfway saw another Saints penalty and another Myler kick.
Flood responded as Phil Dowson was penalised for not rolling away, narrowing the gap to three.
But Saints were standing up to what was being thrown at them, counter-attacingk with a cutting edge and North came close to a try, knocking on with the line in sight.
The teams had been locked at 6-6 at the break in the corresponding fixture last season, but Saints were three points better off this time.
That lead was threatened early in the second period as Flood lined up a penalty from the centre spot, but again his ambitious effort missed the target.
Saints needed some early possession and they got it, with huge consequences for Tigers as Corbisiero bashed his way over the line after the forwards went through the phases.
Myler made a fine conversion from wide left and the away team held a 16-6 lead with 32 minutes left on the clock.
Saints’ fly-half was pulling the strings, putting pace on the ball and keeping his side on the front foot and they came close to another try as Dickinson was held up over the line.
Tigers relieved the pressure by winning a penalty from the resulting scrum and the home fans were starting to find their voices in the bid to get their team back in the game.
They had a big opportunity with 20 minutes to go, but Jordan Crane’s pass was poor at the key moment and Saints had a let-off as the ball was knocked on into touch.
Some superb defending saw the men in lime green hold out on their own line before front row replacement Alex Waller won a penalty at a scrum to give Saints a penalty.
Myler again made the kick to stretch the lead to 10 points with 13 minutes to go and Northampton were sensing a long-awaited win at Welford Road.
But Leicester had other ideas, with Vereniki Goneva making a big break to earn a penalty and Flood reducing the deficit to seven with the resulting penalty.
Lawes was yellow carded for his infringement but Leicester’s Louis Deacon joined him in the bin for dissent.
With Burrell off injured, Saints were shorn of two big players for the final 10 minutes and Tigers were ramping up the pressure minute by minute.
The home fans could sense a try and they were to get one as Slater found a gap and crossed the line.
Flood levelled the score with the successful conversion and the Tigers had the smell of blood in their nostrils.
Their No.10 was now starting to dictate the game and a superb grubber kick into the left corner gave Leicester a chance to pounce for the win.
But Lee Dickson pinched the ball as it emerged from the scrum and set Jamie Elliott away, with the wing’s kick going into touch as an enthralling game reached its conclusion.
Leicester: Scully; Morris, Goneva, Allen (Bowden 70), Thompstone; Flood, B Youngs (Mele 70); Mulipola, T Youngs, Cole, Deacon, Kitchener, Slater, Salvi, Crane.
Replacements: Briggs, Stankovich, Balmain, de Chaves, Waldrom, Williams.
Saints: Foden; Elliott, G Pisi, Burrell (Wilson 70), North; Myler, L Dickson; Corbisiero (A Waller 64), Hartley (c), Mercey (Denman 64), Manoa, Lawes, Wood, Dowson, Dickinson.
Replacements: Haywood, van Velze, Clark, Fotuali’i, K Pisi.
Referee: JP Doyle