Norwich City will need to show patience in their attempts to nurse Jon Rowe back to full fitness.
The winger, who is the Canaries' highest scorer this season, missed Saturday's 1-0 victory over QPR with a heel injury that saw him withdraw from England U21 duty over the international break.
Rowe has been dealing with the issue since before City's defeat to Blackburn but was able to play through the pain barrier against Rovers and Cardiff. He has continued his assessment and treatment throughout the pause on club football.
There was even a fitness test on Friday to determine his capability to feature on Saturday - but it was deemed impossible for him to be involved in the matchday squad.
City's attack missed his influence during the victory - registering just one shot on target against the Championship strugglers, which Hwang Ui-jo converted to secure the 1-0 victory.
The complexity of Rowe's injury means that City can do little more than allow him rest and time for the issue to resolve itself before thrusting him back into Championship action. He is a major doubt for Tuesday's trip to Watford.
"Jonny Rowe still has problems with his heel. This is something that is very difficult to predict because you can't do anything apart from offloading him and it will heal," City boss Wagner said.
"Will it take two days? Will it take 20 days? Nobody knows. You cannot do anything. No injection or anything.
"He made a test on Friday, but he was not able to make it, and we have to look from day to day as to whether it is good enough for him to be back in the race."
Rowe isn't the only winger sidelined for City with Polish international Przemyslaw Placheta also unavailable due to a fitness issue.
"Przemmy (Placheta) had something fall on his toes, and this meant he was not able to make the matchday squad," Wagner said. "We will have to see how he looks for Tuesday."
Norwich are hoping to welcome first-choice goalkeeper Angus Gunn, captain Grant Hanley, Adam Forshaw and striker Josh Sargent back from the treatment table in the coming weeks to ease their injury woes.
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