What a turnaround! A month ago everything in Wasps' garden was rosy with European qualification already assured and the completion of a five-match winning run culminating in a thrilling 52-44 victory at Bath.
In the opposite camp were Saints with one win in 14 competitive matches.
The tide turned rapidly with Northampton winning three on the bounce as Wasps followed up their crushing 49-17 defeat to Harlequins with a second home loss.
It was no more than Wasps deserved as their ill-discipline and poor decision-making saw them concede a 22-point halftime advantage from which they couldn't recover to allow Saints to win a very poor game without them being anywhere near impressive. If you're thinking of having a punt on the Premiership this season check out new customer offers for Coral.
Wasps director of rugby Lee Blackett said: “We were miles better than last week. We had greater speed and intent but our execution wasn't good enough.
“We had enough opportunities to score but didn't take them and our ill-discipline proved costly.” That ill-discipline brought yellow cards in quick succession for Kieran Brookes and James Gaskell.
Blackett added: “It's frustrating as the 14 points we conceded when down to 13 men had a big effect and they scored their points a bit easier than we did.” Northampton made the better start and took an early lead when James Grayson kicked a simple penalty.
In response Wasps built up their first period of pressure and were awarded three easily kickable penalties. However each time they elected not to take them and it proved the wrong decision as the award of a scrum penalty allowed the visitors to eventually relieve the onslaught.
Saints immediately made them pay by scoring the first try. After a strong touchline run from Ollie Sleightholme put the Wasps' defence on the back foot, Shaun Adendorff was up in support to force his way over for his third try in two games.
Worse was to follow for the home side when they lost two forwards in quick succession to the sin-bin. First tighthead Brookes carelessly charged into a ruck to make contact with Sam Matavesi and then second row Gaskell followed for an off-the-ball challenge.
Reduced to 13 players, Wasps had no hope of stopping a formidable 25m lineout drive from Saints, which resulted in Matavesi crashing over.
Saints soon scored their third when Taqele Naiyaravoro went in from close range with another conversion from Grayson giving his side a 22-0 interval lead.
Within three minutes of the restart, Wasps produced their first flowing movement and it paid dividends as Rob Miller crossed for an excellent try.
The hosts received further encouragement when Naiyaravoro was yellow carded for a high tackle but they suffered an injury setback when replacement prop, Simon McIntyre, was led off with a leg injury only a minute after coming onto the field.
Naiyaravoro returned from the sin-bin with no damage done to the scoreboard but Wasps came back into contention with a penalty from the recently introduced Jacob Umaga.
Piers Francis was then yellow carded for a deliberate offside and Wasps took immediate advantage with a try from Tommy Taylor.
But the hosts could get no nearer and had to be content with a losing bonus point.
Wasps v Northampton Saints – player ratings
WASPS: Miller 6 (Umaga 58, 6), Kibirige 5, Fekitoa 6, Gopperth 6 (Le-Bourgeois 52, 6), Minozzi 6, Atkinson 5, Wolstenholme 6 (Vellacott 58, 6), Harris 6 (McIntyre 52-53, 6), Cruse 6 (Taylor 50, 6) Brookes 4 (Toomaga-Allen 56, 6), Cardall 6 (Vukasinovic 56, 6), Gaskell 4, Willis 6 (Morris 63, 6), Shields (c) 6, Oghre 6
NORTHAMPTON: Freeman 6, Sleightholme 7, Hutchinson 7, Francis 6, Naiyaravoro 5 (Tuala 64, 6), Grayson 6, Mitchell 7 (James 64, 6), Waller (co-c) 6 (Van Wyk 60, 6), Matavesi 7 (Haywood 60, 6), Hill 6 (Franks 60- 64, 6), Ribbans 7, Moon 6 (Coles 20, 6), Isiekwe 8, Adendorff 8 (Wood 60, 6), Ludlam (co-c) 7
Not used: Collins
REFEREE: Adam Leal
Star man: Nick Isiekwe – Northampton
