Northampton equalled their biggest-ever Premiership win over East Midlands rivals Leicester as they beat the 14-man Tigers 40-17 at Franklin's Gardens.

With the extra man Saints blew Tigers away as they got three unanswered tries to all-but secure a play-off spot.

The loss loss means Leicester's hopes of a top four finish hang by a thread.

They are three points off the top four having played a game more than their rivals while Saints know they will have a five-point lead at the top of the table come the end of the weekend.

Northampton's defence did well to repel Tigers twice when they were in striking distance of their line in the opening 10 minutes.

But when the hosts had Elliot Millar-Mills sin-binned for a head-on-head tackle Tigers stuck as they kicked the resulting penalty to the corner, and Julian Montoya was mauled over from the line-out.

George Furbank and Handre Pollard traded penalties before Saints' first proper foray into Tigers territory saw Alex Mitchell held up the 28th minute after sustained pressure on the visitors' line.

A second Furbank penalty got Saints close before Tigers' Jasper Wiese was yellow-carded five minutes from the break and Tom Litchfield knocked the ball on under the posts as Saint again went close.

But the hosts flew out of the blocks in the second half as hooker Curtis Langdon galloped down the left flank like a winger after James Ramm's pass for their first try, to put them 11-10 ahead.

It got better for the hosts four minutes later as Jamie Shillcock's deliberate knock-on saw Saints extend their lead to eight points and the full-back go to the sin bin.

But Tigers closed the gap to one point as Wiese crashed over from a close-range line-out after Ollie Chessum's acrobatic catch.

But the game turned after Kata's dangerous tackle on Dingwall four minutes later which saw the floodgates open.

Robbie Smith was mauled over from a close-range line-out before Fin Smith superbly set fellow replacement Tommy Freeman free and he teed up Hendy to go over.

Tom James completed the rout as he pounced on Phil Cokanasiga's 73rd-minute effort before Smith knocked over a late drop goal.

Northampton: Ramm; Hendy, Litchfield, Dingwall, Seabrook; Furbank, Mitchell; Waller, Langdon, Millar Mills, Moon, Mayanavanua, Coles, Ludlam (capt), Augustus

Replacements: Smith, Haffar, Davison, Lockett, Graham, James, Smith, Freeman

Sin-bin: Millar-Mills (9), Hendy (71)

Leicester: Shillcock; Steward, Kelly, Kata, Hassell-Collins; Pollard, van Poortvliet; Cronin, Montoya, Cole, Wells, Chessum, Carnduff, Reffell, Wiese

Replacements: Clare, van Wyk, Hurd, Hatherell, Cracknell, Youngs, Cokanasiga, Brown

Sin-bin: Wiese (36), Shillcock (47)

Sent off: Kata (60)

Referee: Christophe Ridley