Wigan are said to be very interested in signing the player.
The 32-year-old didn’t even have a squad number at the start of the season as it was expected that he would be leaving the club as Big Sam had no plans for him.
But now, after Roberts has hit two goals in four games, Sam has changed his mind and wants the striker to stay, promising him games if he keeps up recent performances.
"He is a player who wanted to make a statement and is doing very well at it," said Allardyce. "He has played his way back into the team.
"We said at the end of the transfer deadline: 'look you haven't got where you thought you were going to get.
'You thought you were going to get away and you haven't. So you are still a part of the team and if you prove you are the best player to play we will play you'.
"He is forcing his way in and is almost the number one selection for me."