Chris Hughton’s side swooped to sign the Poland international on transfer deadline day with Grosicki agreeing terms on a one-year loan.
But it is understood the paperwork for the deal was submitted 21 seconds after the 5pm deadline.
Almost a week on, the EFL is yet to confirm whether or not the deal can go through with Forest having instructed lawyers in a bid to help their case.
Reports in Grosicki’s native Poland suggest confirmation on whether the move has gone through could arrive today.
But if the 32-year-old doesn’t get the green light to move to the City Ground, Albion expect to be able to name him in their Premier League squad.
All clubs had to submit their 25-man squads to the Premier League on Tuesday.
But Albion submitted just 24 names – leaving space for Grosicki to be registered if he returns.
Meanwhile, head coach Slaven Bilic admitted Karlan Grant’s performance in the goalless draw with Burnley ‘put a smile on his face’.
After drawn-out negotiations, Grant joined the Baggies from Huddersfield last Thursday.
The striker had been training on his own prior to the move.
But Bilic opted to give him his debut against Sean Dyche’s side on Monday.
And the head coach was pleased with what he saw.
“He (Grant) is really good at running in behind, he’s good with the ball at his feet – he put a smile on my face,” Bilic said when asked about Grant’s debut.
“He showed me more than enough to know that he’ll be very important for us.
“We took a risk against Burnley because his last game was a few months ago, when Huddersfield played West Brom towards the end of last season.
“He’s going to become better, fitter, match fitter, he’ll get to know the players and their movements and he’ll gel.”
Grant was always the number one transfer target for Bilic and technical director Luke Dowling this summer.
But the Baggies looked both in the UK and abroad to find the right forward.
And Club Brugge striker Emmanuel Dennis has claimed Albion made contact with his representatives about a potential move to The Hawthorns.
“Wages were not the problem – the wages were crazy,” the Nigerian international said. “And I have also played enough international matches (to obtain a work permit).
“The problem was that it was a loan and with the (option to buy) clause in the contract.
“I want to prove myself in England. Maybe you play five matches at West Brom and another club will come and get you.
“But honestly, I didn’t really care. I wasn’t pushing for a transfer.
“I had an attitude of ‘If they buy me, then I go. If they don’t buy me, I’ll stay and go elsewhere later.
“West Brom was a good deal. If they stayed in the Premier League, they would have bought me.
“Then I would have been playing in the Premier League for at least two years.
“But if they dropped again, another team could still have picked me up.”