Replacement flanker Sam Harding also touched down for Northampton, with Bruce Reihana adding two conversions and a penalty in the Saints' best display of the season so far.
By contrast Worcester made a string of unforced errors and looked a shadow of the side that troubled champions Wasps six days ago and Sione Tuamoheloa's late try converted by Shane Drahm was all they had to show for their efforts.
Cohen insisted he is hungrier than ever for a return to the international ranks.
His career on that front has ground to a halt since England's World Cup victory in 2003 and he was omitted from coach Andy Robinson's squad for the autumn internationals last week.
But the 27-year-old said: "You want to play at the highest level possible and I definitely want some more of it - I'm still hungry.
"If England comes along then it's fantastic.
"I don't pick the England team, but all I know is that I'm enjoying playing for Northampton and I haven't been enjoying playing for a long time."
James Simpson-Daniel produced another try-scoring performance in advance of England's upcoming Tests as Gloucester grounded the Ospreys 23-7 at Kingsholm.
Simpson-Daniel, who touched down on his return from injury against Northampton last weekend, pounced for Gloucester's opening try in a scrappy Pool A encounter.
He scored inside the opening minute, but Gloucester had to wait until the 77th for their clincher when centre Henry Paul crashed over.
Fly-half Ludovic Mercier booted 13 points, while flanker Steve Tandy claimed an Ospreys try which fly-half Matthew Jones converted.
Gloucester boss Dean Ryan claimed his team had cleared "a pretty big hurdle" with their victory.
"I never expected it not to be hard work - it was one of our toughest examinations of the season," said Ryan.
"We are happy to clear what was a pretty big hurdle, and that was a different game from the Premiership in that it posed a different set of challenges."
Ospreys coach Lyn Jones recognised his team now face a difficult task to progress.
"It was a good game of rugby, but it fell apart for us in the second half. We had opportunities to put the pressure on, but we didn't take those," said Jones.
"We are missing a lot of players, but that is no excuse for not putting some decent stuff together. We are not out of the competition just yet, but we need to improve."
Bristol's second string gave neighbours Bath a scare in Pool A before finally running out of steam in losing 25-10.
Four second-half penalties by Olly Barkley eased Bath ahead before they clinched victory with a late try from Welsh teenager Tom Cheeseman. Pieter Dixon scored their opening try deep in first-half stoppage time.
Bristol coach Richard Hill rested all 15 of the team who lost at London Irish last week, declaring that Guinness Premiership survival is his primary goal and their only touchdown came from scrum-half Greg Nicholls.
Bath coach John Connolly had no quarrel with Hill's decision to field an under-strength side.
"It was a good call, and I have no problems with it," said Connolly.
"His goal is to stay up, and that's a sensible approach. It does de-value the competition, but clubs are prioritising the competitions they target."
Connolly confirmed he will be leaving Bath at the end of next month.
On the question of a replacement, he said: "The club is looking at a couple of options. I've spoken to a couple of people myself."
Jonah Lomu's new side Cardiff Blues scored a comprehensive 37-20 victory over Saracens, picking up a bonus point for four tries.
The Blues, buoyed by wins in their last two Celtic League matches, subjected their Guinness Premiership opponents to a torrid time with fly-half Nicky Robinson claiming 22 points, including one of their four tries.
Craig Morgan, Jamie Robinson and Robin Sowden-Taylor were the other Cardiff try scorers.
Saracens managed to get their game back on track in the second half and even managed to move within a score, claiming tries through Matt Cairns and Kevin Sorrell, but Cardiff's tremendous defence made sure the London-based side added no further points.