Manchester United midfielder Ravel Morrison was this lunchtime having a medical with West Ham.
Press Association Sport understands that providing there are no unexpected hitches, the 18-year-old will join the Championship promotion hopefuls before the transfer deadline at 11pm tonight.
The Manchester United teenager has had a chequered career so far.
However, although United wanted him to stay, Morrison has opted to cut his ties with the Old Trafford outfit.
"The deal is not quite done yet but we are hopeful it will be completed," Allardyce told the London Evening Standard.
"Ravel is a talented lad and if he really wants to be a player then we will help him as much as we can along the way.
"Perhaps a change of environment will be beneficial to him and help him make that step up to first team football quicker than perhaps would have been the case at Manchester United. There is no doubt he has exceptional talent."
Morrison's contract was due to expire in the summer and the teenager had been offered an extension by the Old Trafford outfit.
However, United were also willing to sell the player now rather than risk losing him to a fee that would be decided by a tribunal in the summer.
The youngster - who will be 19 on Thursday - has been mired in controversy throughout his fledgling career and there are some on the Red Devils staff who believe his huge potential will never be fulfilled.
A member of the triumphant FA Youth Cup-winning side last term, it was anticipated Morrison - rated as one of the best prospects to come through the United academy since Paul Scholes in that famous Class of 92 - would make a breakthrough this season.
Instead, he has been restricted to just two substitute appearances - both in the Carling Cup - and did not even manage a place on the bench throughout Sir Alex Ferguson's massive injury problems.
Although Ferguson has been reluctant to discuss Morrison in public, it is almost certain he would have spoken to old friend Sam Allardyce before the Hammers made their move.
It was claimed by a source close to the deal last night that there was a "50-50" chance of Morrison leaving United before the transfer window closes, although it is becoming increasingly likely the Manchester-born youngster will move.