Northampton boss Jim Mallinder says the severity of a knee injury suffered by England full-back Ben Foden has yet to be determined.
Foden was helped off the pitch in the 18-0 win over Newcastle after jarring his knee while taking a high ball in the first half and twisting it again after the interval.
It was not until the 58th minute that James Wilson touched down, with Luther Burrell adding a second five minutes later, but there was concern over Foden despite the win.
"We need to look at Ben, he was struggling to walk off. Fingers-crossed there is nothing wrong there," Mallinder said.
"We knew it was going to be hard work breaking down Newcastle, they have got a big heavy pack, they defend very well and we weren't quite as fluent in attack as we would like to be."
Mallinder is hopeful that England duo Dylan Hartley and Tom Wood will be back at Worcester next Saturday, but he confirmed Alex Corbisiero will be out for three to four months after an operation on his knee.
Newcastle director of rugby Dean Richards was furious with namesake referee Dean Richards after his side were shut out at Franklin's Gardens.
"We got absolutely nothing from the referee or the touch judges," Richards said.
"When you look at it in slow motion you can't understand where they are coming from with the decisions they make.
"All you want is a bit of parity in the decision making and we didn't get that from the officials. The scrum was a lottery.
"When you have people riding up on the outside of the scrum, the loosehead coming in at an angle at every scrum, you can't understand how they get to the conclusion they do.
"But we transgress once and we get penalised. Some teams get away with it and other teams don't.
"At the breakdown, if we are being penalised for competing for the ball then they need to be as well, there is no consistency. I'm angry and frustrated."