Saints boss Dowson delivers latest updates on Coles, Mitchell and Mayanavanua
Alex Coles is in contention to face Exeter Chiefs on Saturday, but Alex Mitchell remains likely to be sidelined for Saints.
Coles has been recovering from a soft tissue injury and did not feature at Bath last Friday, while Mitchell continues to get medical advice on a neck problem.
When asked about England lock Coles, Saints boss Phil Dowson said: "He's good. He'll be there or thereabouts this weekend.
"With soft tissue stuff you always worry about coming back too soon so we're being very careful on that front, but he should be there or thereabouts."
When asked whether Mitchell could play this weekend, Dowson said: "Probably not. He's seeing the specialist again on Thursday so we'll have more of an update then in terms of timeline and what it looks like."
Temo Mayanavanua helped Fiji to clinch Pacific Nations Cup glory last Saturday as they beat Japan in the final in Osaka.
The lock has now headed back to Northampton to rejoin his Saints team-mates.
"It was brilliant for him and then he's had to get on a flight straight back to Northampton so he's on the way home," Dowson said.
"He's had a very good tournament down in the southern hemisphere so we're excited about getting him back in and getting the jet lag out of him. Hopefully he'll be available soon.
"He's going to get the full MOT when he gets in, to make sure he's okay, see where he is mentally.
"We'll try to get him turned around and ready to go."