Coach Mike McDaniel told reporters Monday that Achane was being further evaluated for a knee injury he sustained in Sunday's 31-16 win over the New York Giants, but declined to comment on the severity of the injury or what specific testing was being done.
"It's just something we're treating that we'll get more information on," McDaniel said. "He was in and out of the game, a standard rotation. ... He thought he might have something, but he's such a tough kid. It was kind of tough to read, so we needed to evaluate more, and that's what we're doing today."
Without Achane in the lineup, veteran Raheem Mostert, the NFL's co-leader in rushing touchdowns, is in line for a heavier workload. A source told ESPN the Dolphins will also activate the practice window for running back Jeff Wilson Jr., who has spent the first four weeks of the season on injured reserve with multiple injuries.
Achane has been highly effective through his first four games with the Dolphins. His 460 rushing yards ranks second in the NFL behind Christian McCaffrey, and his 12.1 yards per carry average is nearly 5 yards greater than that of the next closest player this season, Breece Hall (7.2).
His yards per carry average is also the highest in NFL history through a team's first five games of a season, according to ESPN Stats & Info research.
On the strength of Achane's performances over the past three weeks, the Dolphins lead the NFL in passing, rushing and scoring while accumulating the most yards of offense through five games in NFL history.