North injured during Saints success
A controversial red card for Wasps' Nathan Hughes saw Northampton come from behind to win a tumultuous clash 52-30 at Franklin's Gardens and move 14 points clear at the top of the Premiership.
Hughes was sent off for kneeing Northampton and British Lions winger George North in the head as he scored Saints' and his second try.
The Wasps number eight complained it was unintentional, but after watching replays on the big screen, referee Craig Maxwell-Keys decided to issue a red card five minutes before half-time.
After suffering concussion in Wales's opening Six Nations match against England, when he was knocked out twice, there were worrying scenes as North lay motionless on the ground.
He started moving shortly afterwards as medics attended to him before he was stretchered from the pitch.
A minute before the incident, after 34 minutes, Alex Lozowski kicked a penalty to put Wasps 20-8 in front, but they went in 27-20 down at half-time after a dramatic turnaround saw Northampton add two tries from lineout drives after North's try.
And yet it was Hughes who inspired Wasps' opening try after four minutes when he turned over George Pisi on the visitors' 22. Wasps shifted the ball to the wing to set Christian Wade free, and speed home. Lozowski added the conversion.
Northampton hit straight back as Stephen Myler fired a crossfield kick into the arms of North to score, while Myler hit the post with the conversion to leave Wasps 7-5 in front.
The home side were offside at the restart allowing Lozowski to add three more points and the fly-half then showed an electric turn of pace to skip through a gap to send Wade flying over, while Lozowski converted from the touchline to make it 17-5 after 20 minutes.
Myler and Lozowski exchanged penalties, before the match-turning incident.
Samu Manoa caught the re-start and sent North powering into the corner, but as he grounded the ball the Hughes ran into him, kneeing the Welsh winger in the head.
North appeared knocked out, lying motionless for a short while. As the medics got to him he started moving and after a lengthy delay he was stretchered off.
Meanwhile, Maxwell-Keys showed Hughes a red card. Hughes complained to the referee as he walked off and a Wasps water carrier - conditioning coach Dan Baugh - had to be pulled away as he argued with Saints forwards coach Dorian West on the touchline.
After a long wait Myler missed the touchline conversion, but Saints had a penalty from the restart and Myler booted it into the corner.
Saints' maul steamrollered towards the line only to be dragged down and Maxwell-Keys awarded a penalty try. Myler's conversion suddenly made it 20-20.
On the brink of half-time, Saints kicked another penalty to the corner and as their maul piled towards the line, Alex Corbisiero broke off to touch down and M yler converted to make it 27-20.
Facing 40 minutes with 14 men Lozowski kicked a penalty as Wasps moved number eight Ashley Johnson to hooker and managed to win a scrum against the head on Saints' 22.
They moved the ball wide where Daly drew two men before offloading to Wade. Lozowski landed the touchline conversion to make it 33-30 with 11 minutes left.
The comeback was short lived though, as three minutes later Ken Pisi touched down and two tries in two minutes from Ahsee Tuala, plus two conversions by Myler saw Northampton bring up the half-century.