Brentford midfielder Vitaly Janelt has returned to training after recovering from a knee injury.
Janelt was withdrawn during the Bees' 2-0 win over Southampton in March and has missed the last two games against Leicester City and Brighton and Hove Albion.
Head coach Thomas Frank revealed that the 24-year-old was back 'on the grass' on Monday - but believes Wednesday's game against Manchester United may come too soon for him.
Frank also stated that Janelt's midfield colleague Frank Onyeka will miss the game with a hamstring problem.
"Frank has a minor, minor injury," said the Bees boss.
"Vita had the knee problem but very good news: it was a minor injury against Southampton and he was on the grass today which is positive.
"But it will probably be too early for Wednesday night. Frank will be out for Wednesday."
Manchester United also have some absentees and will be without two of their key players, Christian Eriksen and Casemiro, for the Bees' visit to Old Trafford.
Eriksen has been out since January with an ankle injury sustained in an FA Cup match with Reading, while Casemiro will serve the third match of his four-game ban after being sent off against Southampton.
But Frank is well aware that the Red Devils have plenty of quality to plug the gaps left by the duo.
"They have very good players, no matter what," he said.
"Let's say Fred and [Scott] McTominay play there, they are very good and are doing fantastic in many ways.
"I guess Manchester United think that Eriksen and Casemiro are two of their better players and every team wants their best players on the pitch.
"But United have such a strong squad - they will put a decent team out there!
"They will create problems for us on Wednesday night but, of course, they'd like to have their best players on the pitch."