Sanchez Watt has been ruled out of Leeds United's clash with Coventry City, with the injured winger facing another week-and-a-half on the sidelines.
Watt missed Tuesday night's game at Hull City due to a hamstring strain sustained against Portsmouth on January 22, and he will undergo further treatment in the coming days in an attempt to return to contention for United's fixture at Bristol City next weekend.
The on-loan Arsenal youngster saw a specialist last week and was not considered for selection at the KC Stadium, where striker Davide Somma took his starting place and scored United's second goal in a 2-2 draw.
Grayson admitted that Somma's performance – coming on the back of goalscoring outings against Scunthorpe United and Portsmouth – had enhanced his prospects of a second successive start this Saturday, but Watt will play no part against Coventry at Elland Road as Leeds work to resolve his latest injury worry.
Grayson said: "He tweaked his hamstring in the Portsmouth game and he's probably going to be out for another 10 days or so."
Watt had made a positive impression on United's Championship season since joining the club from Arsenal on a year-long loan in August, but his campaign has been riddled by fitness concerns.
An ankle problem sustained in October sidelined him until the turn of the year, and his latest injury has forced him back into the treatment room at a time when the 19-year-old appeared to be returning to prominence within Grayson's squad.
His absence in Hull offered a rare chance to Somma, pictured right, who made his first start since the middle of November and responded by scoring his 10th goal of the season.
Grayson altered an established formation to accommodate the South African international alongside Luciano Becchio up front, and three finishes in his last three league appearances have given Somma a strong
chance of retaining his place this weekend.
Grayson said: "We're got players who can come in and do a job when we need them to and Somma's shown his quality and his eye for goal again.
"We normally play with Luciano up front on his own but I felt that an extra striker would work Hull harder.
"Putting another midfielder in would have been a risk because Neil Kilkenny was only just back from the Asian Cup and I wasn't prepared to start him. Opportunities are there to be taken and Davide's done that again."