Northampton director of rugby Jim Mallinder admitted that his side’s absences in the second row proved costly in their defeat to Sale.
Samu Manoa, Christian Day and Courtney Lawes were all unavailable on Saturday.
Sam Dickinson and Calum Clark filled in, with Dickinson also seeing yellow in the first half, as Saints fell to only their third loss of the season in the league.
“You need players in specialist positions and one of those positions is big, tall and heavy second rows. Unfortunately, we ran out of them today, but it’s one of those things,” said Mallinder.
“I thought the two men who stepped in worked their socks off. It was a great effort from them but on the day, we just weren’t good enough.
“I will be putting quite a lot of pressure on our medics over the next few days to make sure that they’re all back.
“Samu’s in America and he will return tomorrow (Sunday) and the injury situation is looking quite positive, so all three should be fit for next week (against the Ospreys).”