Two strikes from replacement fly-half Stephen Myler enabled treble-chasing Northampton to stretch their long unbeaten home run to 21 matches.
But last weekend’s LV= Cup winners, who are also chasing the Guinness Premiership title and the Heineken Cup, were pushed all the way by Wasps in their top-four clash at Franklin’s Gardens.
Wasps’ England flanker Tom Rees, playing his first match of the season after two shoulder operations, looked to be heading for a winning return when substitute Dave Walder took over the kicking duties from Danny Cipriani to boot his side ahead with a 65th-minute penalty.
But, five minutes after replacing Shane Geraghty, rugby league convert Myler hit a superbly-struck right-footed drop-goal to restore his side’s lead before adding a penalty four minutes later.
Wasps had most of the play in the first half but failed to capitalise and went in 8-6 behind after number eight Roger Wilson finished off the final move before the interval with a try in the right-hand corner.
After soaking up the pressure, Northampton broke out of defence, with Geraghty setting up the assault which put them ahead.
His break saw props Brian Mujati and Soane Tonga’uiha both drive hard into the Wasps defence before the home side switched the ball the full width of the pitch where left-wing Bruce Reihana’s long, curling pass found Wilson, who held off Tom Varndell’s try-saving tackle.
Reihana had given Northampton the lead in the 10th minute with a 45-metre penalty.
Two minutes later Cipriani, who had missed from long range in the seventh minute, made amends, equalising from in front of the posts.
Cipriani missed a relatively easy penalty in the 16th minute but edged his side 6-3 ahead with a simple 28th-minute effort.
The Australia-bound number 10 and his lively half-back partner Joe Simpson, returning after dislocating his shoulder against Harlequins in December, were causing the Saints plenty of problems.
Cipriani’s half-break and quick off-load down the middle set up a promising spell of pressure but it came to nothing when England prop Tim Payne spilled the ball as he tried to drive over near the Northampton posts.
Another excellent burst from Cipriani on the halfway line set up a promising move but Toulon-bound former England winger Paul Sackey hesitated and was impressively tackled from behind by Mujati, showing impressive pace for a prop.
Reihana was short with another 45-metre penalty and Geraghty failed to convert Wilson’s try from the touchline.
The Saints took the game to their opponents in the first half as the barnstorming Tonga’uiha, bound for Saracens at the end of the season, was causing havoc in the visiting defence and when Wasps finally broke out they were brought 40 metres back for a lineout when Ben Jacobs haplessly kicked the ball out on the full.
The visitors came again and looked odds-on to score when Varndell, in flight, found fellow wing Sackey but Saints flanker Neil Best foiled him with a brilliant try-saving tackle.
Wasps were in the ascendancy again but were denied a try when Cipriani crossed in the 59th minute only to be brought back because Varndell’s pass was forward.
But they went ahead after another fine move involving Dominic Waldouck, Cipriani and Varndell produced a penalty landed by Walder, the 58th-minute replacement for Steve Kefu. But Myler had the final say for second-placed Northampton.