Yedlin was not involved against Reading on Tuesday night, having suffered a knock in the club’s win over Brighton and Hove Albion late last month.
And Benitez – whose side take on Fulham at St James’s Park tomorrow – revealed at the Madejski Stadium that he feared that the defender had suffered a “small tear” in his thigh.
Newcastle hoped that Yedlin – who has been assessed this week by the club’s medical team – could be back within a fortnight.
But that initial assessment of the injury suffered by 23-year-old Yedlin looks to be optimistic.
Speaking after the Reading game on Tuesday night, Benitez said: “Yedlin didn’t realise he had the problem against Brighton.
“We protected him against Huddersfield, but he had to come on. But he was complaining, and you could see that maybe it would be one week or two weeks. He had a knock. Maybe has a small tear.”
Benitez – whose side lead the Championship by three points – could give an update today when he speaks to the media ahead of the Fulham game.
United’s manager, however, has Vurnon Anita back from injury, while the experienced Jesus Gamez is another option.
Anita – who has alternated at right-back with Yedlin – made his comeback from an ankle problem in the club’s win over Huddersfield Town last weekend.
Benitez fielded 31-year-old Gamez, signed from Atletico Madrid last summer, in the goalless draw at Reading.
“He knows his job,” said Benitez. “Defensively, it was not an easy game, because they have some pace.
“But I think he was OK. When you have a new player playing, you cannot expect that he will be the best in the team, but I think he did fine.”
Meanwhile, Benitez has few other injury concerns.
Winger Rolando Aarons is back in training after recovering from a long-term knee injury, while midfielder Isaac Hayden is recovering from ankle surgery.